I'm 19 years old, I have cystic acne mainly on my forehead, and some on my jawline near my ears, and I first experienced acne at 16. My mom has never had acne and my dad has adult acne. My acne tends to come and go, and I have combination skin. In the past, i have been able to clear my acne up with medications such as clindamycin, oral antibiotics, retinas, and sulfate washes and experienced several month periods without any pimples and just oily skin. This year it came back when it usually comes back, right before I start school, and it was the worst it has ever been. So I started on Tazorac, clindamycin gel, an oral antibiotic, and dapsone, which has drastically helped my acne. But I wanted to know if anyone could tell me, from their past experience with acne, what could be the cause of my acne and if in their opinion if I am likely to grow out of it. There is no way that my diet could be causing my acne as I have a very restricted diet, for the most part I stay on top of my skin regimen, I exercise almost daily, change my shower towels/pillowcases, I try not to touch my skin as little as possible. I was thinking it could be pubertal acne seeing as I hit puberty only 3 years ago (which is when it started), but I wanted to hear other peoples opinions on what the cause could be and if I'm likely to outgrow it. 
Quote... This year it came back when it usually comes back, right before I start school, ...
Do you get really anxious before starting school? If so, it seems that your acne is probably hormonal, in which case a very important step to manage it is to manage stress. Also, do you discontinue treatment when your skin clears up? Typically, anyone who suffers from at least moderate acne will have to stick to their routine for quite awhile to keep it from returning. As for specifically how long that is, we're mostly at the mercy of our genetics. It's likely to taper off when you're in your twenties, but for some of us it's a much longer wait, if it even goes away at all.