mental road blocks?

Im not really sure what my deal is, my husband and i have been trying for a baby for over a year nown which is something I've wanted as long as i can remember. I've only been pregnant once which ended in miscarriage at 7 weeks about a year before i started dating my husband. i have PCOS and have been on metformin treatments for several years and periods are pretty regular, he has been tested and definitely not the problem. i am probably 50 lbs over weight (60 if I'm being real with myself) i Know a huge part of the problem is the weight but for some reason i can not make myself diet and exercise.... i have joined groups, weight watchers, even a biggest loser contest at my work and nothing motivates me. i feel like there is some sort of mental block there that i cant seem to over come. I've struggled nearly my whole life with depression and thanks to my former job i deal with a great deal of anxiety and ptsd. Its also getting to the point that i dont even want to have sex and i cant figure out what the deal is, i love my husband more than anything, im extremely attracted to him, i enjoy sex when we do get there but its not very often which is also slowing down the baby making process... i dont know quite what im looking for other than wondering if anyone else has hit mental road blocks like this and maybe what worked for them?