Hugs honey, it is a lot to cope with but you will get there. I often find that some of the other issues melt away if an LO is on an age appropriate routine, so why not start with that and then work on the feed to sleep prop and NWs once you're getting slightly better naps?
A good age appropriate A time would be around 2 hrs 30 mins to 3 hours. So if he wakes at 7 then you would aim for the first nap between 9.30 and 10am. You may well find for a few days that he still short naps even once you've extended the A time. You can extend either slowly in 15 min changes every three or four days. Given that you have quite a shift to make and he is obviously in a UT/OT loop now I would be tempted to make the shift fairly quickly and just go for the longer A time straight away.
If you get a short nap (less than 1.5 hours) you'll need to slightly shorten the second A time (go for 30 mins less than the full A you tried for the first nap) and put down for his second nap. If you get a good first nap, stick with the same A time for the second nap. This could look like:
WU 7am
Nap 1 10-11.30
Nap 2 2.30-4
BT 7pm
Obviously this is not necessarily what you will get. But if you aim for the longer A time and keep a record of his sleep for a few days and then post here we can help you with tweaking it.
Then you could work on the feeding to sleep next and sleep training using other methods for NWs and resettling naps. In my own humble opinion there is little point tying to ST when the A times are too short - there will be lots of effort for little gain. Good luck xxx