Need advice..

Ok so I am 27 a single mother of two amazing kids a 3 and a 5 year old.. so I have been dating this new guy for 3 months and I had two very heavy periods last month and here we are on the 17th of December and I still have not had one this month.. i took a pg test and it was negative is it just to early or what.. any advice would be greatly appreciated.. I never have had this happen before and I am just curious if anyone e has ever experienced this or something like this before