Sounds like you just need a simple training program to get things going as you don't seem to be going via the "get a trainer" route (no problem with that, it does cost $).
RPE, I suggest, is for lifters who know their body after a year or more of progressive training.
Why not just try 5/3/1 for 3 months and see how you go. You can find the book online. It's pretty simple and you can get spreadsheets and apps and such to work it all out for you very quickly. It will push you every week and give you a deload every month. I got my biggest gains on this program and packed on a bunch of muscle as well.