I am about 8 weeks pregnant and nearly 18 years old but since I've been pregnant if my fiancé sucks my nipples in foreplay they will bleed a bit, its happened to both nipples bit its only happened since I've been pregnant... is this anything to worry about? Me and my fiancé are getting quite worried.

You should go to the doctor and ask them. They have better answers.

Sucking on the nipples that hard isn't good whether you're pregnant. Get him to calm down and let them nipples heal. Going to the doctor would be a good idea too to make sure nothing is damaged.