Is it normal for my adult tooth to be lose at age 15?

My adult tooth has been lose for years now and I didnt know at the time that once an adult tooth is gone it can never grow back again, and now that it's kinda lose and aches sometimes I realized this is very serious as a 15 year old I didn't expect my tooth to be lose at a young age, I know it probably bc I don't regularly brush my teeth since I only brush then when I take a shower since I wanna do it all at once, but last night it aches a bit that I actually felt it and immediately brushed my teeth, I learned that, if u have a lose teeth u should never wiggle it out or try to pull it out or eat any sticky food but I didn't knew at the time and I guess it progressively became more lose than before need help on what to do as an 15 year old, or am I even a 15 years old or just have problem with height and lied about been born young.