you need to sit down and evaluate everything, diet, routine, sleep, and make sure that everything is in check and has been for a while. It is hard to tell when you have reached your natural peak. You stated that you have stayed the same weight, give or take 5lbs, after lifting for 2 years. IMO there hasnt been much of a natural gain at all. You should have been able to make better gains than that over a 2 year period. You need to change things up naturally before turning to gear. Change your diet, use other suppliments such as protein, glutamine, and creatine. I made excellent gains naturally over a 2 year stretch. There is definately room to grow naturally bro, i wouldnt recommend gear yet, give it another year or so of lifting naturally.