Question about my Teeth?

Hello, I was worried a bit about my 4 front teeth, the ones that cut the foods and stuff. For a while now, my front teeth have been feeling lose. Like, I wiggle them with my finger and they wobble a bit. I am worried because I already lost my baby teeth and these are the ones that don't grow back. If they fall out for some reason, I'm screwed. They aren't like completely lose, only a little bit. I was wondering why they were. The only possible reasons I can think of are that they are getting loose because I chew my nails a lot or because I NEVER drink any milk. Please help?