so I'm 24/25, im a petite person and I always have been. always been able to eat whatever I want, whenever I want and…

so I'm 24/25, im a petite person and I always have been. always been able to eat whatever I want, whenever I want and not gain a pound. even after my 1st pregnancy (I was 18) I just had my 2nd child almost 2 months ago, and I guess bc I ate SO BAD while being pregnant, I've been eating a lot of salads, fruits, healthy foods. I've been doing "dance fitness" at least 2 hours once a week. I've been feeling really good about my change of lifestyle. I gained 35 lbs during pregnancy, and since then ive lost 20. but now I'm starting to eat more fast food, I'm drinking a lot more coffee, and my weight is starting to rise again (which I'm not used to). can any moms give me any advice for determination, or tell me what you do to stay positive about you weight? I will add: my boyfriend is amazing and does a good job with making me feel good about myself. but I wanna personally feel good about myself. any advice?