Gums on bottom row of teeth very tender and stingy, just noticed they are all white and thin, upper row is pink and thick, what could bottom ones be?

White lesions: There are a number of different things that can cause white gums including yeast infections. It's best to go see a dentist and a full diagnosis.

Wisdom teeth: This could be your wisdom teeth trying to come through or getting infected. Go see a dentist and get this evaluated before it becomes a big problem.

Seek help: red, angry, puffy gums may not be healthy. Thin white gums may not be healthy. You need to be examined by a professional. Ask your Dentist if you should see a qualified Periodontist.

It is normal: Yes, wisdom teeth can grow at age 13, especially if you've been maturing faster than others.