hello everybody! i need help

Hi! I am a 20 year old female. I have had clear skin my whole life....(the occasional pimple or two ..nothing recurring or persistent at all)...and when I would get these occasional little whiteheads, it would be in my T-zone. I have NEVER EVER EVER had a pimple on my cheeks before. Well, I was taking no medication...nothing. I had never been to a dermatologist and never thought I would ever need to. I figured I lucked out...and I was never going to get acne! but..NOT SO!
.....starting this past October, I started getting pimples on both sides of my face on my cheeks. At first, I just thought it was strange, cause i had never gotten any zits there in my life. Then, it just was continous from that day on. I was freaking out. I still am...6 months later. I went to the dermatologist to see if he could put an end to this...I actually broke down crying in his office...saying I had never had anything like this before and will it go away? He prescribed me tetracycline..which I have been on since Thanksgiving. I am taking 250 mg. twice a day. And, over Christmas break...I went to the girl doctor ..because I hadn't had a period in six months. She prescribed me Ocella, which is the generic brand of Yasmin, (and I also have never been on BC at all)....I told her I was strictly taking it to clear my face. ALL i want is my skin back. THe skin that I've had for twenty years. I'm doing everything I know to do. I'm drinking buttloads of water. I'm eating healthy. I'm taking my antibiotics twice a day. I'm taking my birth control. I'm applying my Differin cream nightly ..religiously. I'm praying. I'm doing everything I can possibly do. And I'm still getting new pimples on my cheeks. I will do anything to make this go away. This doesn't run in my family. No one in my family has even so much as had a zit. I am just so.....in shock and I feel like the ugliest girl everytime I look in the mirror. There has got to be an answer! and a solution. I will not stop looking until I find something that works. I will add...that I had sex for the first time in September...and then three weeks later...my face started doing this. I have asked numerous people if that could have been the culprit for my break out, and they all say no. But I swear, that was only thing that was different. Does anyone know ..just a guess at what else I should do? or? guess at the longevity of such a break out? I mean, I'm going on six months here..and I'm really hoping I'm not going to have this when I'm 25 or 30. I just..want this to end. I am hibernating in my room. and I just can't handle this anymore. I'll take any advice I can get.