help me, im scared !! First pregancy , I think im shy of 9 weeks

Okay so me and my guy hadn't been getting along, I decided to take a pregnancy test and it came back positive. So I went to the hospital and they confirmed my pregnancy , it's been about 4 days since I found out. 2 nights ago I went to the restroom and I noticed light pink blood, but only when I wipe. (I had sex this same day) None on the pad , and none in my underwear. I was freaking out so I went to the hospital. They did an ultrasound, the Doctor comes in and Immediately goes to tell me he didn't see my baby on the ultrasound and that I may or may not be pregnant. I'm freaking out now because even though I hadn't digest the fact I maybe pregnant this is now terrifying. I'm kind of young (20yrs)and I don't really understand everything that's going on. This would be my first pregnancy. So they do a urine test and before it could turn he says" it's negative " you aren't pregnant but im waiting on the guy to come take my blood . He comes in takes my blood and by the time he leaves I go over to see that the urine test is definitely positive. So I'm really confused now. I go over to the nurse and we talk for a brief second. I'm frantic and she confirms to me the urine test is positive and that it may not be that bad so I need to calm down. Scared out of my mind I'm waiting for the results to my blood. The Doctor comes back in he says your hcg levels are low you may be threatening a miscarriage and to come back Monday But this cannot be I'm not bleeding that much. I'm actually only cramping .It actually stopped by the time I got home. It just now started back about 30mins ago . is this normal? Has this ever happened to anyone? It's only light pink not red. According to the paperwork a miscarriage is heavy red and gives me reason to change the pad .