I'm an 18 year old girl who waxes her underarms often. at first, my hair kept getting thinner and thinner and i was very satisfied. i wouldn't do it more than once a month. since last month, my right underarm has been growing a lot of hair. is this normal

Hair growth: Hair growth ( thickness and speed ) and hair density are completely independent of waxing. There is nothing you can do to speed it up or slow it down - other than to mess with your hormones in a major way. ( Spironolactone and minoxidil included...) Your extra hair growth is not really "extra" it is just returning to what it was before. Take a picture and compare.