I agree, I think relaxation is your problem, but it doesn't seem like your key problem. I think you have psychological issues and need to really talk to someone. You say you are over your trauma, but some people never fully recover from such things mentally. I would ask your GP to refer you to a good councellor, someone you can really open up to and get your problems into the open. Once you stop feeling alone and can share with someone, everything becomes brighter and easier. Meds work short term but soon lose their effect, so not a good route to take. The mind is a strange machine, sometimes we dont even realise it has a problem.
stress/anxiety WILL cause palpitations. Try belly breathing. If you do it everyday after a couple of weeks i promise you will see results with your palpitations and sleep.
stay away from sleeping meds.
But if u must since your sleep problems seem to me stress/anxiety related i'd suggest ativan