12 weeks pregnant not showing up on hpt

So I'm 12 weeks and one day pregnant. I found out last week I was pregnant BC I went to hospital with pain in my right side. They said the test showed negative but the soon says I have 2 baby's in there. Well yesterday just for the heck of it to see if it would show up I took a hpt and still says BFN. I don't understand. I have pcos could this make it not show up on a test?? I just want a home test to show my mom BC I lost paper work from hospital.