I am not sure about the effects of spironolactone on HPT's, but I do know that a positive...no matter how faint....is a positive. Usually that just means that your horomone levels are just low (<1).
I would call your doctor, inform them that you have had multiple faint positives that have been increasing in levels. They will probably run a blood test or do an ultrasound. It's best to get checked out by a medical professional at this point, just to be sure. Until then maybe start some vitamins and eat healthy! Good luck!