I am worried about my pregnancy. i am 8w heard a heart beat of 171 at 7w 6d. really no symptoms. could something be wrong?

Unlikely: Pregnancy is a normal, natural condition and, in an otherwise healthy woman your age, they usually progress normally. If a heartbeat was heard and you are not having any symptoms of pelvic pain or bleeding, try not to worry so much. If you continue to be so worried, see your OB or midwife again, and consider some counseling or joining a support group. Just take good care of yourself!