Why cant i lose weight? Has anyone tried pink patch?

I lost 21lbs after having a baby and it has crept back on over past 7 months. I have tried loads of diets. Cambridge aggitated my acid reflux, atkins I put on 6lb and I followed I it to the LETTER. Slimming world I gained weight and weight watchers just stay the same every week no matter how hard I try. I keep getting emails about a pink patch, do you know if it works and what else can I try?