I may have tubal pregnancy

So, i went to the doctors because my periods really late, about 3 weeks late, and don't know why....they gave me a urine test, and it turned out lightly positive, so they gave me an ulrtasound, and couldn't find anything except som liquid where my fallopian tubes are, so they gave me a blood test to see how serious this whole thing is, and how much hcg i had in my blood. when the results came back, the hcg count in my blood was 29, so either i could've just gotten pregnant, or i may have been pregnant and it just went no where, but as of right now, its supposedly not serious, but i have to go back in two days to check my blood count again, hopefully get a way better idea of whats going on, what do you all think?? has anyone had this experience before?? i need someone elses input please, im really scared, please, thank you,
~Marie~