I brush my teeth everyday and I don't eat too many sweets, but my teeth seems to keep getting worse and worse they seem to be slowly deteriorating.?

See your dentist. Continue to do good oral hygiene. Make sure you use floride toothpaste. Don't forget to floss. Eat a good diet including calcium rich foods (mild, yogurt). Some people have weak enamel which can predispose them to tooth decay despite their best efforts. See your dentist to discuss treatment options.
Teeth. You may be a mouth breather which cause significant dryness of mouth while sleeping. See your dentist.