having trouble sleeping, and other issues...

The most important way to sleep better is to be consistent. Go to bed at x time, get up at y time. Initially it's going to be rough. Make sure to get out and get some sun and drink coffee, as soon as you wake up. Exercise early in the morning is also highly recommended. Also wind down one hour before night. Lower the light, read a book (phone use and tv isn't recommended). This should help for most people.
The thoughts and flashbacls sound like counseling might be useful. It's important to not exaggerate the importance of thoughts, just let them pass. Practise mindfulness (very important). Journaling is good to get past events out of your system.

 

This is my routine before going to sleep:
1) Breathing exercises (I use Wim Hof Method)
2) Cold shower followed by….
3) Warm bath or shower
4) Prayer

Works like a dream!

 

"Sleep psychologists" are supposedly a thing now. If you don't wanna go that route, which I don't blame you, I strongly recommend a mild, non-prescription sedative like valerian root or l-theanine.