Hi Gaby and welcome to BW!
It could well may be the wonder week and in that case you just need to wait things out. I am reluctant to tell you to increase the A time because most babies his age are doing 2h as their A times. If in a few days, when the week is behind you, you still have 45min naps and difficult to settle for sleep then I *would* increase his A time to 2:10 and stick with that for 3-4 days to see if it's working.
It looks like his first nap right now might be UT and because he doesn't sleep enough for it then he ends up OT for the next one and the rest of the day.
1:40 - 5:10 \ activity
This is a very very long A time for a baby his age, I really wouldn't let him do more than 2-2:15h A time at the most right now. This very long A brought him to bed OT and it was difficult for him to fall asleep.
Re feeding, are you BF or FF?
Usually at this age when LO starts to take less at 3h or 3.5h in your case it means that they are ready for the feeds to be more spaced. You could try and offer the feed 20min later than what you do now and see if it makes a difference.
He was supposed to take a nap now, but after an hour of him crying (I tried PU/PD and pat/shush and none of it worked) I couldn't take it anymore.
Tracey meant for PU/PD to be a last resort, after pat/shh has been tried and didn't work. It's true that PU/PD is suitable for babies over 4m but in reality many young babies find it hard. I would leave it for now IIWY and focus more on pat/shh. It does take a while till it works but if you do it right and do exactly the same thing for every sleep then he'll get the hang of it in a few days. Consistency is the key.
HTH, hun, hugs, I know how hard sleep issues can be.