I'm a beginner :/ please help..

At my high school, there are three different PE classes: Team Sports, Aerobics, and Body Tone/Conditioning.

I've been wanting to grow my glutes and shrink my waist for an hourglass shape so I joined Body Tone as it involves a mixture of cardio and weightlifting. It's been about 4 weeks since I've been in it and I'm starting to see muscle gains in my legs and arms but, I feel as if my stomach is getting bigger and not smaller. I've been feeling bloated really often, especially when I eat after working out. Also, although I'm gaining muscle in my arms, they actually appear bigger as well and I don't think I have shed any fat off.

Since I am taking a PE class, I don't decide what workouts to do for the day; different workouts are assigned. And I'm not really satisfied with the results I'm seeing on my body so far. I liked how petite and skinny I was, I just wanted to shape my body with some curves without getting too bulky.

I've watched some videos on YouTube to educate myself and I learned that heavy weighted oblique exercises will make the waist appear more boxy than curvy but, I'm still pretty lost with what to do. Should I do more cardio in my free time to try and shed more fat off? How do I achieve the hourglass shape but also keep my petite size?