Having a hard time losing weight

Hi! I’m an 18 year old girl. I’m about 5’4 and around 165 pounds. Recently I’ve put on about 10 pounds and I’m just starting to notice the weight on my body. I’ve been eating pretty unhealthy so it’s not like I don’t know why I’m gaining so much weight. I’ve been going to the gym 3-4 times a week and have started eating healthier again while maintaining a strict calorie intake on a vegan diet but nothing seems to work! At the gym I do about 15 minutes of cardio on the treadmill, and workout and thigh workouts because I want to slim my stomach down again and tone my bigger thighs. I’m not sure what I’m doing wrong but I’m not seeing any résultas does anyone recommend a good and safe way to lose weight? What do you suggest!