How to lose 20 lbs in a month and a half?

I’m clueless. The only thing that worked for me was my high school weight training coach. I’ve done weight training for a long time and I usually don’t lose weight. I just got back to the gym and I’m 190. Scale keeps going up instead of down and I don’t know why. I don’t want to starve ☹️ I’m okay with eating just a little, I eat a little. My boyfriend will have his last USMC ball and all of his friends and their wives are skinny. It’s just us that are overweight. Two of them will be parents and are gaining weight but that’s because they will be parents. I feel bad, I want to look my best for him. My lowest ever was 145 and now I’m up to 190. I don’t know what to do! I could possibly go vegan or vegetarian but I need options or recommendations because I don’t know how! It’s frustrating.