Training twice a week + Skinny fat

[Zabulon]

Well, I'm a young teacher so yes, I guess that I live in a pretty stressful environment!
My current program :
Squat 4x5
Bench Press 4x5
weighted chin ups 5x6-8
Lateral Raises (high reps)
Rows 4x5

(I change the order of exercises a bit from one workout to the other)

I really use challenging weights (for me!) but I have been plateauing for quite some time now. I always end the last set by grinding the last reps. In the end, the problem might be that i'm afraid of gaining fat. I'm afraid that although the weights would go up with a larger caloric input, I would end up as I have once been.
In fact, I've been stuck in this for some years now haha.

Thanks for your input, I've read all your answers carefully.