Positive hm preg test but negative blood test : S

Im sssoo confused. I was on Estelle 35 (contraceptive pill) but had forgotten to take a few days, and then ran out. After discussing it with my husband (who knew Id forgotten to take it a few times)we decided that I wouldnt go back on it and we would let my cycle get back to normal and try for a baby in a few months. I have now been off it for around 12 days and only had very very light spot bleeding (3 days after i stopped the pill) and it only lasted a matter of hours. I waited a week from the and did a home pregnacy test whch came back positive (a faint second line). Last nite I was cramping and it was causing me worry so I went and saw a doctor at the hospital who did blood tests. The blood tests came back negative, and when i was told it was negative I was too upset to ask the doctor what might be going on. I also have a metalic taste in my mouth, breasts feel fuller but not at all sore and still no period or any signs its coming. I have no idea what on earth is going on and am wondering if this has happened to anyone else, or if anyone could offer any kind of explanation. Thanks