I've had my 3 month old lab just over a week now.. and she has had soft poos the whole time and at times it seems to have blood in it what could this be?she seems very happy and well

It could be any one of a number of things unfortunately.
Biggest culprit for those symptoms is worms, get a stool sample and take it into your vets to be tested.
You can get specimen jars from pharmacies or just from your vets.