Confused...thin blood? i dont understand?

I'm confused about this because my Dad has thick blood and is on blood thinners but I think I might have thin blood? Today I received a shot and the blood went all the way down my arm and stained my pants...and it was thin. I'm not sure if I bleed excessively. Also, I sometimes find myself with an increased heart rate and it would be very random. But wouldn't that lead to thicker blood? I don't know anything about this and I'm not sure if thin blood is a good thing to have, but I guess it could be because it doesn't clot and cause heart attacks but then again if i get cut would it not clot fast enough? I'm just confused and I don't know what's wrong with me? What do you think?