I just read that aspirin isn't safe to use during pregnancy. I had really bad headaches and morning sickness I didn't want to use extra strength tylenol so I used 500 mg aspirin with stomach guard instead. Should I be worried at all? Also now that I know it may cause miscariages, I won't be taking it anymore. I only took it a few times, maybe three mornings in a row, and I only took one. What damage may this have done? If any.

Most likely you have done no damage. Consistent use is what causes the damage.

Extra Strength Tylenol is perfectly safe to take during pregnancy.