Ok, last paragarph tells me your testosterone production is down. How much fat do you eat each day, what types of fat, and are you eating hydrogenated oil (which blocks the absorbsion of many efa's)?
12 sets per body part once a week? Too much volume for you in each workout, and you are not hitting body parts frequintly enough. High set, low frequincy training is a crutch that steroid using bodybuilders can often get away with, but a natural with less than great genetics isn't going to make gains that way. Have you considered a low volume (2 or 3 sets per body part) 3 times a week?
What town do you live in? If it has a sizable population there should be a Gold's or a Powerhouse gym there. Your gym is a pussy gym and the staff and employees will have a bad attitude, which in turn, can effect your training and progress.
I use alot of machines (I do heavy free weights as well though including deadlifts) and hit each bodypart 3 times a week. I'm 5'9" 230, about 10% bf with 18.5" arms. So that PT may not necissarily be full of it.
Please answer my fat question and be as specific as possible. Type of fat, amount of each type, what percentage of your calories come from fat etc. I think that is a major issue here. I think you could stand to increase the protien a bit.