I’m sorry you’re struggling with this, I had the exact same experience with my first who is now 2.5 years old.
unfortunately nothing much helped but I can share some of the things I would absolutely not do again now I’ve had my second baby.
First of all I truly put the effort in to try and establish routines like nap times within correct wake windows and getting her in her cot even if it took an hour. I work in childcare so my belief and experience in establishing routines won despite the fact that it wasn’t working.
I would absolutely advise not to drive yourself mad trying and trying to establish things that just aren’t working. Your baby just needs what he needs and it’ll be so much worse for you when things keep failing instead of just going with what he needs.
my daughter also hated the car and pushchair, it was awful and I let it dictate us going out all the time, we couldn’t go far, we couldn’t go out for long because she’d need a nap, and we couldn’t do baby groups or meet with people because it would always fall when she needed a nap. Don’t do it, don’t let it take over, go out and just try to accept that his naps won’t be perfect.
its very hard because you don’t want your baby to be grumpy and overtired and you won’t enjoy things if they are, but what I learnt was that I was way more miserable letting it run everything rather than just going out and risking some crying. If I’d met up with friends they could’ve taken a turn cuddling her, if I’d gone to a baby group maybe the distraction would’ve been good for her.
I most definitely had Post Natal Depression and I think it was only magnified by trying to control and improve the situation. Just try to go with it and I promise it gets better eventually. And if he’s your only one, just enjoy the cuddles and the fact that you can give your all to one child without worrying about another one missing out on your attention. Accept help if you have any and it’s all normal, and it’s all temporary x