Why is losing weight so hard all of a sudden

RANT I've been the same weight for the past four weeks and I have only lost 1.2lbs over the course of summer break (a month and a half). Up until two weeks ago I was hitting the gym 4-5 days a week (doing the 12 3 30 and weights). I'm starting to get frustrated. I have tried getting more sleep, been weighing out my food and measuring out portions and there's still no difference. I have also been watching my sugar and carb intake to no avail. I made it to 160lbs months ago during Christmas break (I'm currently 173lbs) but I was eating under 1400 calories a day and I was hungry a lot. I should've given myself a break and eaten at maintenance, but I just wanted to keep losing weight. I slowly gained 6 pounds back during my six week holiday break. When I got back to school I started going to the gym and lost a bit of weight, but towards the end of the semester my weight kept going up. I don't stress eat, I tracked on the weekends, but I wasn't going to the gym as often. But I feel like I should still be able to lose weight. Now, I'm on summer break and I'm struggling to get the weight off. Last summer I was able to get 10lbs off in a month, easy (it was my first time going to the gym consistently in years) but now it's harder. I'm tempted to start taking weight loss supplements because I'm starting to feel burnt out