Its not unusual for shorter guys to bulk up better. You dont have as far to move the weight.
Sucks about your shoulder, I had an impingement recently due to biciptal tendonitis in my left shoulder, took a month to heal, 3 days in a sling, icing 20 min every hour, absolutely no overhead use. Theres a reason I do all my presses on the ground because the added range of motion on a bench just puts the shoulder at risk.
I havent gotten an official diagnosis on the sciatica. But Im certain it is, My mom has it, and its the same shit for me as well. Ive learned all the stretches to help with it, its possible it could have to do directly with the vertabrae. But im finding leg presses and hamstring curls have helped a lot - its mostly my physical work that can lead to flare ups. Thees also some amazing core routines that help as well.
With a routine I usually find something I havent done that targets the body part Im training, Ill do that for a month or month and a half then change it up. Sometimes Ill through in a high volume high rep routine every so often. I really recommend this website:
www.scoobysworkshop.comThis guy is a 50 year old bodybuilder - he never uses a bench press and is a mostly vegetarian. Whats great is he gives all the right info so you can save money and improve. My last 6 month of success are from his information.