I had an adult tooth grow before my baby tooth fell out, but I think it was a molar from memory. My dentist just told me to keep wiggling it. In the end I pulled it out myself (I think I was about 10. I used string and a door )
Personally, I wouldn't worry about whether the adult teeth are all going to fit until they start popping through. Kids' jaws keep growing with their bodies and our teeth move around to fill gaps. I wouldn't start worrying yet