Help:(

So I'm 12 days late for my period. I got a positive test like 2 days ago. I took another today but it was negative, or at least so faint I couldn't see it. I have a bump, back pain, slight cramps, extra tired, super hungry, definitely moody, and no bleeding, so I don't think it was a chemical pregnancy. Can anyone tell me what might be going on? I have another test to take with morning urine, but what should I do if that comes up negative?? I was so excited, I hope I didn't lose the baby:(