What's the Name of That Book??? discussion

I read this book in 2016. It was about a teen girl who was slightly overweight and constantly ridiculed by her mother over it. She eventually gave in and ordered a dieting program online, with barely edible food and a hard workout DVD. She also got a job at a pretzel shop at the mall (I think it was pretzels? Some kind of fast food). The main character had a little sister. The mom eventually found out about the dieting program and encouraged the main character to continue it, even giving her money to keep purchasing the program. The main character is trying to lose weight for a wedding set several months from the book. A few scenes I remember are: 1. the main character gets stuck in a dress while trying it on. 2. while at the pretzel stand, the main character meets a cute guy. He tells her he's "glad to be her first", referring to the pretzel he receives as being the first pretzel she's made on the job. 3. The main character works on the workout DVD at home. There are 2 instructors (I think one was named Trish??) doing different energy levels of the same routine, but the main character gets too out of breath to keep up with even the lower-energy version. Anyone have any idea what this book could be? Thanks!

I know exactly what book your referring to, it is one of my favorites, could it be
45 pounds, More Or Less by Kelly Barson?

45 Pounds by K.A. Barson - Jessica's suggestion

Yes, that's exactly it! Thank you so much.