Firstly hun, stop stressing, stress can make you gain weight
Secondly you need to kick start that metabolism again, so maybe have lots of small snacks a day, synned of course, so that it doesn't get time to nap, loads of water and maybe jiggle with your exercise, it will work, I had the same thing and so did my daughter just a few weeks ago she lost 8lb after sts or gain for 8 weeks, then bang changed her exercise from walking and running to swimming and kick boxing and reassessed her foods and gave them a shake up and she has constantly lost 2-3lbs since then...and like you she was adamant it wasn't working and she was ready to throw the towel in, she only kept at it cos i told her I was going to drag her to class if I had to lol come to think if it, if you decide to give up I will come find you and drag you back to class too...that's not a threat, that's a promise...You can do it hun I promise you xxx