How else can I stay on my diet?

I need encouragement! So after years of yo-yo dieting, I’ve hit an all time low and spent the last month and a half starving myself. Sure, I lost a good 20 pounds, but I also lost my energy, tolerance, and my period. When I came to my parents house for the weekend, I realized this was unrealistic to keep up any longer.. I had quite a binge on things I never let myself eat. I’ve decided ONCE AND FOR ALL to live the healthy way, with breakfast lunch and dinner, no snacks (well, every once in a while), and regular exercise (im starting cardio boxing classes tuesday, and also spinning, and running plus HIIT) I am expecting to gain a little at first… and then lose a bit or at least tone up at where I am. Is this a good expectation? I am excited to finally live a lifestyle that has a realistic possibility of maintaining life-long weight control. But I know as soon as my body starts to change at first (since I lost all that weight and am now starting to eat again) that I’m going to question whether or not I should relapse to my former lifestyle. Words of encouragement please!! especially from anyone who has done this change before

Also, what are some good healthy weight-loss aiding foods to buy for when I go shopping? I’ve been googling (ha) and so far I’ve found Grapefruit Sardines Canned Pumpkin Yogurt as must-haves. Obviously there is much more to learn! But these are things that are supposed to be like “hidden gems” or whatever. I’d appreciate any other tips you guys have!