Your post is two months old but I wanted to comment anyway. Hope you check back in on this thread.
I can relate to your misery over weight gain. Unfortunately, obesity is a main component of PCOS. Us women are slaves to our endocrine system. The slightest thing can cause us to gain weight. Even if you didn't have PCOS, stress can cause weight gain. Worst, is sleep deprivation. Your endocrine system is directly connected to your body clock. It's a vicious cycle: weight gain causes stress, stress causes insomnia, insomnia causes stress, stress causes weight gain. It's brutal.
I don't know if there is anything I can say to help you, other than what I'm sure you already know, which is to be on top of your diet like crazy. It's the best weapon you have-- don't put anything into your body that isn't super healthy. Exercise every day, no matter how busy you are. As for not sleeping, this is a serious problem. I have several different sleep disorders and rarely sleep more than five hours and sometimes I am awake for up to two days. It's a mess and I know it is a major contributor to my obesity.
I went from 104 pounds to 287 pounds in less than two years. I didn't menstruate for 10 years. Then I got this really bad hive outbreak, started menstruating again and gradually lost weight. Over a three year period, I lost 113 pounds. Even though I was still obese, it was a huge improvement. The weight loss slowed to a crawl and then stopped altogether.
It is important to note that I was eating an extremely healthy diet and was enjoying the benefits of human companionship. Being in love and being loved was comforting and made me very content which helped to counteract the enormous stress I was and still am under. Shortly after my boyfriend broke up with me, I started gaining weight again and I know it is because I no longer have that happiness in my life. My life is once again, day to day drudgery. I haven't gone all the way back up to 287 but I'm sure I will in another year or so.
My best advice to you is to do whatever you can to reduce your stress and get your sleep back on track. As for your distress at wanting to lose weight because you are getting married in two years-- I could write a thesis on that. You need to recognize that you are going through a grieving process. The loss of your health and the loss of your attractive figure is utterly devastating. Most women with PCOS, regardless of what meds they take, will usually always be overweight to some extent.
By the way, the fact that my boyfriend accepted me as I was and was still attracted to me despite being so heavy, is something that I consider a blessing. If you are engaged, obviously your husband-to-be loves you no matter what you look like. If you pressure yourself to lose weight for your wedding, you may actually sabotage yourself by putting too much pressure on yourself. It's a very personal thing and something that you will have to come to terms with as you may not lose as much weight as you hope to.