nighttime and naptime routines and other questions

My son has been fighting naps horribly for more than a month now (before I could just pick him up and nurse him and he'd fall asleep easy, now it often takes an hour+ of carrying him around, nursing, etc before he settles) we cosleep at night and usually for naps so I'm having a really hard time figuring out how to get him to sleep without nursing since I'm right there, except part of why he isn't sleeping well seems to be that he's getting full nursing and can't nurse anymore but can't fall asleep and gets upset about it. He had a tongue and lip tie that weren't discovered until 7 weeks so during those first 7 weeks he was nursing non stop and still wasn't getting enough and would cry if I put him down because he was hungry so that's why we ended up cosleeping, and then I had to switch to pumping and bottle feeding for him to get enough so I allowed him to comfort nurse to sleep in an attempt to keep him nursing for when he was able to transfer milk properly...which happened about a month ago. At night he goes to sleep much easier, and often when he's done nursing he'll settle himself to sleep by staring at the light and shadows coming through the curtain, but he doesn't do this at naptime (light quality different?) and recently he's also started waking up in the middle of the night and he can't get back to sleep. If I show any sign that I'm awake at this point then he starts crying, so I just lie there next to him and hope he settles, but he stays awake for a long time usually and he's grumpy all day. I'm trying to bulk up his routine to hopefully help get him drowsy but he just seems like he can't settle even when he's exhausted. Right now for bedtime I read 2 books, carry him around the apt a couple times while singing the same song, just added bath time to the routine (though he always cries when I take him out of the tub-how do you keep the room warm enough but not so warm that it's a sids risk for bedtime? Our apt is usually like 73 degrees but I used to make it warmer for bathtime, don't feel comfortable having it warmer at bedtime but I think he's cold coming out of the bath) then I put an overnight diaper, pajamas on. I give him a small bottle of pumped milk just for routine sake though yesterday he only had a couple sips before fussing so maybe I'll phase that out, then I play his musical light up seahorse toy and nurse him, he usually eats til full then alternates between nursing, looking at the seahorse, looking and the window and "sings" until he goes to sleep. Recently it's taken him a lot longer to settle at night and sometimes he tries really hard but gets frustrated after awhile and starts crying and I have to pick him up for awhile then try again. I sneak out of the room after he falls asleep to go pump and spend time in the living room, and he used to usually sleep a few hours straight before waking up for the first time, but now he usually wakes up within an hour and I have to rush back in and nurse him back to sleep then decide whether it's worth sneaking back out of the room. Naptime I change his diaper then either take him for a walk in a baby carrier or walk him around the apartment a few times while singing the same song, bring him into the bedroom, turn on his seahorse and nurse him but I usually end up having to pick him back up and walk him again sometimes several times before he'll settle. After all this most of the time his naps are only half an hour, and he's only taking 3 a day, so he's super tired. Any recommendations? What are your routines? How do I soothe him without nursing and without CIO type methods? Isn't 5 months too young for sleep training anyway? How do I put him down drowsy but awake? Everytime I try he quickly works himself up crying.

Sorry for the ramblyness of this, baby woke up so I've been typing off and on while playing with him