Why do you want to waste the effort trying to change someone into what they're not?
You clearly resent your girlfriend. Based on your stated parameters, you have two choices: control her eating habits and exercise regimen, or dump her. The first is orders of magnitude more shitty than the second.
Look, this is all a function of time. She wants to eat, be happy, and perhaps get a little chubby. Maybe when she tries to fit into her favorite dress, she'll be like, damn, gotta hit the gym. Or maybe she'll dismiss it entirely -- it's her choice. On your end, you're also putting in work (more than me, admittedly) in maintaining a healthy lifestyle. If that's a priority for you, then find someone who's a better fit.
Honestly, the longer I do this shit, the more I realize that there are certain things that are simply undeniable dealbreakers: (1) religion, (2) wanting or not wanting kids, (3) partying or not partying, and (4) focusing on health or not.
To anchor that into reality, the current girl I'm seeing? Not religious, not baby crazy, and will pound beers or raspberry Stoli on a Saturday night with me at an EDM show before working her ass off at the gym Mon-Fri so she stays thin.
If you want someone who'll count macros and wake up at 6am Sunday morning for a run, that's not your current girl, but go find someone who is. I will absolutely not be your competition for her.