I would take another test just to confirm a result either way, try a first response one that would definitely show up now. There is a very slight chance you could be pregnant and it was too early with the others but if the next test shows negative then its probably just your body playing tricks on you.
I hope you get a positive result soon hun, try not to stress about it this makes it worse. Relax and have fun trying, it will happen eventually and there's no reason why you shouldn't be able to go full term next time.