Should I wear a bikini, or am I overweight?

In my opinion, I don't think I'm fat at all. However, my family (maily my superficial aunt, geez) calls me overweight and loves to tell me stories that when "she was my age, she was 80 pounds and all the boys were chasing her". I don't have a lack of confidence, I'm actually quite confident in myself, and I'm a charming teenager, but for some reason I'm just not sure whether of not I should wear a bikini! There's a pool party coming on this wekened and I recently tattered up by tankini (I am SO over the tankini phase) and now I need a new one. Btw, I am 5'4" and 126 lbs, a size 4-7. Any suggestions? I want a cute bathing suit but not a skimpy one since I have a little age. My legs are pretty nice as well, since I run a lot, but my thighs are kinda large. Thanks so much!