Back on track: push, push, push

Hi guys, so I have had MFP for two years now. I'm 21 years old. I stopped using it in April of 2012 when I met my boyfriend I was a size 12 at the time, and around 180 lbs. I am now a size 22 and weigh 252. I want to get back on track I was a size 8 in high school and I would really like to go back down to 180 and go down from there. So the reason why I came back to MFP was because I was recently diagnosed with an under active thyroid and I have a tsh level of 52 the normal is between 2 and 5. I need this for my well being it's not about needing motivation or a drive but about knowing that there are other people out there like me struggling with their weight and trying to get back on track. My weight fluctuates a lot because of my thyroid problem, which means I must have a low sodium diet and can only eat certain types of foods. I have a huge sweet tooth and I'm fitting it hard. I recently added photos of myself pictures of a smaller me, I hate looking at those pictures because I wish I was at that point not sick and not trying to loose weight. I recently lost my period and have probabilities of being infertile, but. I just have to keep pushing forward. :) I want a healthier lifestyle and i want to be healthy incase someday I am able to have children. so yeah what's your story?