Okay, so you're at that stage where you're exhausted and a little desperate. I get it. There is so much frustration at that stage and when you're exhausted, you feel guilty, and it turns into this vicious cycle. What you need are some solutions that will work for you and your family!!! :)
I'll tell you what worked for me. It will be another thing for you to consider, but I understand that you'll need to do what works for your family.
First of all, remember that your baby's schedule during the DAY has a huge impact of how he will sleep at night. I BF both of my children to about 13 months. I understand the differences between BF and formula fed babies, BUT that had nothing to do with my children's sleep cycle. NO, I didn't have to start forcing cereal too early to get them to sleep through the night.
Both of my children had terrible GERD (reflux) and were still able to sleep through the night at an early age. My son's first 6 hour stretch was at 6 weeks of age. My daughter's first 6 hour stretch was at 7 weeks of age. Both slept through the night (which I consider to be a 6 hour stretch at this age, building up to a 10-11 hour stretch by 3 months of age) continually from 6/7 weeks on UNLESS they were teething or going through a growth spurt.
For me it was all about Babywise. Get the book and read it during your sleepless nights. :) It's not a long book. I will admit that the first chapter is not extremely interesting, but has lots of info on breastfeeding. Then it gets really interesting. I seriously credit Babywise with both of my children being such good sleepers.
Just a heads up, though....like any other 'method,' people who have never read it will latch on to some misconception and bash it. Whether you try Babywise or Ferber or something else, don't do a fly by the seat of your pants approach where you THINK you're doing the method. Actually read the book and if you decide to commit, then commit.
Things I learned from Babywise....
1.) It's not about feeding on demand. Your body produces hind milk and fore milk. The fore milk is very watery and will just satisfy thirst. It's the milk that first comes out when you're nursing. The HIND milk is what your child needs to satisfy his hunger. If you nurse too often or not long enough on one side, your child could be getting too much fore milk and not enough hind milk to fill his tummy. All milk is not created equally. It would be like expecting you to survive on water all the time and not giving you food. Oh, and the book also teaches you how to check for the appropriate growth signs...you want your baby to be growing appropriately!
2.) It's not about stopping to feed your child every 2-3 hours. It's really not. It's more about setting up a consistent schedule EVERY day where you always feed your child at a certain time. Think about it: would you be confused if one day you ate lunch at 12:00, and the next day at 11:00, and the following day at 1:00...all because of how your day started off? You need to come up with a *flexible* schedule, where you do your feedings at the same time each day, within 15 minutes, and on days when things are a little off, aim to get back on schedule by early afternoon. To this day, I can seriously tell you what both of my children's schedules were at the 6 month mark... They nursed at 6:30am, 9:30am, 12:30pm, 3:30pm, 5:30-6ish, 8:00 (cluster feeding in the evenings), and then slept after the 8pm feeding until 6:30 the next morning. On occasion, during a growth spurt, I would throw in a 10pm feeding for a few days. My babies knew what to expect and when to expect it...just like you expect to eat lunch at noon (or whenever). Plus, it made the scheduling of appointments really easy, because I knew that give or take 10-15 minutes, they would be feeding at those times.
3.) Their PLAY schedule is just as important in them sleeping through the night as their nighttime routine. It all plays into one another.
4.) The sleep cycle....before this book, I truly did not understand a baby's sleep cycle and how many babies do cry out between sleep cycles (usually around the 30-45 minute mark!). How you react to that can make a difference with whether or not your child will go back to sleep. Also, this method promotes training you baby to self sooth so that he can go to sleep without you rocking or nursing him to sleep.
I could go on, but if you're interested in any of these things, then buy or check out the book ("On Becoming Babywise"). Oh, and use your common sense when you read the book. If your baby is crying outside of the normal feed/play/sleep schedule, then it's okay to respond appropriately and feed/soothe your child as needed.
Good luck!