hcg after miscarriage help - please, any thoughts needed🙏🏽

today is 4/21.
my first prenatal appointment was Monday 4/11, I was told my urine was negative and did bloodwork. results were 492. did bloodwork again Wednesday 4/13, results were 220. Thursday my body passed the baby and the sac and everything, shouldn't my levels have been back to 0 by now? they already dropped more than half in less than 48 hours so as low as they were and as fast as they were dropping shouldn't they be gone? I'm asking bc I think I could be pregnant again already. the dr said that I miscarried weeks ago and you are more fertile after a miscarriage. is it possible or am I just struggling accepting the loss or something?🙄 all my symptoms had gone away but they are creeping back up on me and all the feelings I had when I first found out I was pregnant are coming back. 
** also getting positive tests. one yesterday and one today that was darker than yesterday's.
any thoughts or similar experiences??