You sound just like me when my DS was 4 months.
There's a great book called the 'no cry sleep solution' by Elaine Pantly which is full of cry-free ways of helping your baby to sleep.
I could never do CC. Instead, we borrowed from this book and did everything we could to take the stress and cring ot of night times. I really think the cc and the way I was stressing about out had given DS allot of negitive assocations with nighttime. Pretty much as soon as DS twigged that we were doing things on his terms things got MUCH MUCH better.
We settled with this:- Bath, books, breastfeed every night. Cuddles and feed and into the cot very, very sleepy. DS sleeps through until the small hours and then coms in bed with us, has a quick feed and them sleeps through until morning. This isn't everyones cup of tea but its what we wanted and it works for us. And this is from a hysterical crying baby that would wake every two to three hours.
You said that you think you have made things harder for yourself by letting him a fall asleep on the breast. How can giving something to a baby that they find so utterly comforting be a bad thing? If your baby thinks he 'needs' it every time he wakes to go to sleep, then there are cry-free methods where you can gradually and sensitivey break this habit. In the book above, there is a method where by you break the baby off at the end of a feed when he is just suckling, and if he crys, give it back, count to 20, 30 (or whatever number seems to work) and break him off again and eventually he will realise that he doesn't need it to go to sleep. I still let my DS fall slaeep on the breast sometimes , but I know that he doesn't need it every time he wakes up.
Basically, don't be too hard on yourself. You have done nothing but follow your instincts which is the right thing to do. Its only in very recent history in this part of the world that we have expected our babies to sleep in cots away from us. Its a baby's natural instinct to be very close to a parent at night time especially, when we are naturally more vunerable. You can teach a baby that their cot is a nice, safe, place to sleep without putting them them (and yourself) through tramua. It just takes time, patience and maybe a few compromises.
Good luck and things will get better, I promise :