help with weight loss!

So... I'm addicted to soda. I'll admit that. But past two months I have been trying to cut back, I just find myself wanting it more. I'm 265 and 5"10 and I honestly don't look it. I'm going to the gym 3 times a week and have been eating a bit healthier and tell me this I've GAINED 5 pounds since I've started. I drink 6 water bottles a day and I know I need to drink a lot more to help but I just can't get the full motivation to do so. Since my baby I've lost all my body tone, I have squishy fat instead of what I had before and I'm getting really grossed out by my body. I've always been a big girl! But I'm. If and beautiful! But lately im not feeling so beautiful and my fiancé doesn't help with him drinking soda all the time and we eat out so much 😩