TTC but have PCOS and overweight

Okay so I've never posted before, but wanted some help.

My husband and I have been trying for a baby for 5 years with no luck. I have PCOS and I am very overweight. I know losing weight should help, I have tried several times over the last few years at most I lose 2 stone, but then end up putting it all and more back on. I have issues with depression and comfort eating. I currently see a councillor once a week to try and overcome these particular issues. I was just wanting to know if anyone has been in a similar situation and managed to lose the weight then fall pregnant. If so is there anything in particular you did to lose the weight? I feel like a complete failure to my husband. I'm desperate to lose weight to give us the best chance of having a child.

Any advice is appreciated.