is it possible?

Is it possible for there to be nothing wrong with me or bf but we still aren't getting pregnant? We have had 2 miscarriages and I've had a bunch of blood work done and everything was fine or perfect waiting to get his sperm tested we have been trying over a year and no luck I'm starting to really worry I already have a 4 year old but he isn't his real dad plz give me your thoughts I'm so depressed about this