To be honest Beed, it sounds like your child doesn't know how to fall asleep without a prop. (bouncy seat, nursing, being rocked) I think working on that is a good start. I know it can be hard and sometimes we just do what we have to in order to get by but in the long run you want him to be able to sleep without you. Because he needs you to fall asleep and because his sch is not consistant it is hard for him to get the rest he needs, thus overtired.
My first advice is to get him on a good easy sch. You can check out sample sch in the easy forum. Then work on sleep training, not fun, but worth it.
I, as well as others, will be here to give advice and support along the way.
Hang in there.