What does your diet currently look like?
Also, what kind of shape are you in, in terms of bodyfat? Not percentage, but looks-wise - do you have some definition, generally pudgy, etc.?
It's probably a moot point since you were lifting in your teens, but do you think you noticed more results from any of those programs in particular?
A huge part of training is consistency and not mindfucking yourself out of progress just for the sake of some change.
Since you're squatting what you can bench, I'm going to make a leap and suggest that maybe your legs aren't as developed as you think. Any recent pics?
[In before Starting Strength-bashing via mr. popular]
Starting Strength can be a solid program, but it's certainly not a cure-all/must-do for every beginner.
Really, since you've been jumping around so much, you should see good progress if you buckle down and stick to one single well-designed program for at least 12 weeks. Westside for Skinny Bastards is a popular program. Dr. Clay's Blending Size and Strength is another good plan:
But, again, whatever you think you can strap yourself into for a straight three or so months would be the way to go. I'd just be sure to follow a plan written by a coach and not try to design one entirely yourself.
Getting your nutrition in line will help a bunch, but in general, no, you're not going to overtrain just because you're on a bodypart split as long as it's well-designed.