Phantom Lord, it sounds to me like you've got the basics of the game and should move from how's to why's.
Let me guess: you always travel with as big an army as you can, you don't worry about morale, you don't have any party skills over 4, your companions are chosen pretty randomly and you equipped them to be what they were when you recruited them.
It sounds like my first game. I don't think conquering the world is going to happen for you in your current game. The problem is that the enemy lords have been accumulating experience and at this point are very high level which causes you all kinds of problems. I would call this game a learning experience and start over. I could easily have all the progress you've made in 100 days.
There are all kinds of threads around here you should read: about companions and quests and rewards and troops and sieges and ruling.
First, have you installed Diplomacy. It tweaks the game just a little and makes it much better especially later on. Google mount and blade warband diplomacy and you'll find it. I wouldn't install anything but Diplomacy, but make sure you have that.
In this thread I talk about a lot of advanced stuff you'll want to know: http://forums.taleworlds.com/index.php/topic,295668.0.html
You want to play my 2nd game but take the Brain Trust ideas from my third. Get your Str and Ag up to 15, Int to 18, and put every other point into Cha.
But there are some basics that you need too. You need to make relationships. When you start your own kingdom, you will want lords to join you. Each lord has a personality type. The best lords to have are upstanding and good-natured. You should avoid any other type of lord. You definitely don't want bad-tempered, sadistic, or pitiless lords. Your relationship with all upstanding and good-natured lords improves when you gain honor. If your honor gets high enough, these lords will become "locked at 100." That means they'll stay loyal to you no matter what you do to them. Ideally, you want a kingdom with only upstanding and good-natured lords. You should be able to get 12 or even 15 of them eventually. You can recognize those lords by the things they say, but one of the report windows in Diplomacy will let you identify the personality type of any lord you've met.
You get honor by clearing villages of bandits and refusing the reward. You get honor when you release prisoners.
Lords will only join you if they have a bad relationship with their current lord. So early in the game, you want to find the upstanding and good-natured lords who have a low relationship with their liege and court them. Particularly, break into prisons and release their family members. People really like that and it's not terribly hard when you haven't signed on with a kingdom yet.
Specialize your companions. You should take: Alayen, Bahestur, Bunduk, Ymira, Firentis as Fighters. Klethi is the looter. Deshavi is the scout. Jeremus is the medic. Everyone in your group needs as much of the Trainer skill as they are allowed by their Int.
The first thing you do with a fighter is put their Str up to 12. Then you put their Int up to 12 to fill in their skills. Then you put their Ag up to 12. Fighters need Trainer, Power Strike, Ironflesh, Weapon Master, Riding, and Athletics. In that order. They do not need any other skills. Once you have them at 12 Str, Ag, and Int. Put Str up to 18. Put Ag up to 15. Put Str up to 21. Put Ag up to 18. Companions do best on horses with a 2-handed weapon that has no thrust damage. So, give the fighters heavy chargers and heavy great hammers. Blunt damage penetrates armor and takes prisoners that are worth money. Put all the weapon points for companions into 2-handed weapon and crossbow. Give them Masterwork siege crossbows and two bags of steel ammo. They're the greatest archers in sieges.
The looter, the scout, and the medic. I call them the brain trust. Other people have their own names. You want them to get you party skills. I'm still working out the best way to do it.
Hire the other 8 companions. Send them out on their gathering support mission to get you right to rule. Hiring some of them gets you some cheap armor and equipment for the companions you'll use.
Your character should follow the fighter pattern up to Str 15. Then get Ag 15. Then get Cha 12. Then get Int 18. Then put every point into Cha. You first need the fighter skills (don't get Athletics do get Power Draw). Then you need to start developing leader skills. Leadership, Prisoner Management, Inventory Management, Persuasion, and Trade. Unfortunately, you can't just max everything out. You don't get enough skill points. So, you need to plan ahead. Keep in mind that your party gets a +1 bonus to a party skill if you have that skill at 2. In the game, there are books that will give you a +1 bonus to Tactics, Engineering, Wound Treatment, and Surgery. These are all important skills. If you put 1 point in each and get the books, you'll get a +1 bonus for your specialist.
Turn your difficulty all the way up. It might take some getting used to, but do it. In the end, you want all your companions and yourself in plate armor riding heavy chargers. Your fighters will use only hammers in the field and are crossbowmen in a siege. You want a heavy morning star and a huscarl round shield and a Warbow with khergit arrows. You need Power Draw skill 5. I would love to take Horse Archery and Athletics and maybe a couple points of Power Throw but I just don't because I need the skills elsewhere. I played most of the game with an Inventory Management of 4, and that's too low.
At the very start of your next game, have a 12 Str and Ag of 10 or so. Go to the master of the field and train. Then go into the arena and train. Go up levels until you have at least a 12 and 12 in Str and Ag, 4's in the Str and Ag skills, and 600 silvers. Then ask the arena master about tournaments. There are usually four or five at the beginning of the game. Try to win three of them. Roam from town to town hiring your companions, buying bargain equipment (rusty scale armor!), and winning tournaments.
Once you have a party together, become a bandit hunter. Build a small, elite force. Take prisoners. Get rich.
You get renown from beating large forces with small forces. More men in your army means less loot. Means your share of the experience is less. Twenty swadian knights or khergit lancers or slaver chiefs is all you need until your ready to start conquering. Build businesses in every town. Get your companions plate armor. Get yourself lordly armor. Take release prisoner quests from lords and ladies of lords that you're friendly with. Take quests from rhodok villages. Take any farmer in the tavern clear-my-village quest. Take bandit hideout quests.
Once you get started conquering, only ever raid khergit villages and don't do much of that.
