How many naps and how long does your baby take?

My son is 4 month and really doesn't have a good nap schedule I feel like he is always tired he takes a good nap a hour or two after he wakes up than it's like so random.. 20 mins here and there he fights sleep so bad and I think it's because he is over tired I have no clue when I should lay him down I try to do it before he is to tired and he still ends up screaming for ever and not falling asleep I matter how long I let him cry. I feel like my whole day revolves around me getting him to sleep.. he never just falls asleep never I have to put him in the swing and manually rock him in it and some times he will just scream and scream what am I doing wrong! It's consuming me and making me go a little crazy him being so unhappy and me being fusterated because I fell all I do is work on getting him to nap. I tried the crib and letting him cry comforting him letting him cry so on and he gets so worked up I can't even calm him. I know the whole put him down before he is to tired thing and I try so hard to and it always results in the same thing... HELP ME he is screaming bloody murder right 😫😫😫😫😫