I'm 20 and also 5'4 but my goal is 10 lbs more than yours lol.
Word of advice- DIET PILLS? NOOOo0o0o0o0o0o0o0oOOO! throw them out! they never work. It's just people trying to make money. Seriously, if Diet pills worked...would America be the fattest country in the world right now? wouldn't we all be skinny sticks? wouldn't EVERYONE be taking them? seriously, think you should not use them. Do it the RIGHT way, the healthy way. Eating right + exercise= RESULTS. You just have to be patient. Most people start taking diet pills because they have no patience and just want the weight to come off immediately...but really, let's just get real here. Did you gain all that weight in the blink of an eye? no. Therefore, it won't take a blink of an eye to lose it all either. It'll take time. Gradually, it'll come off. Do it the healthy way. With determination and will power, you can do anything. You've made the decision to lose weight---so that shows that you are on the right track, you're aware that something needs to be fixed. But trust me, don't look for the "quick fix". Nothing works that way. You can do this. Just focus on your goal. Focus. Focus. Focus.

Good luck!