Reported miscarriage

So according to docs i officially am in the process of miscarrying. last friday i was having some vaginal bleeding and cramping with hcg levels around 2800. i was told i was only 4 weeks according to the vag u/s. they found the sac but no embryo which doc said was fine because i was so early. bleeding continued over the weekend and cramping got unbearable. tylenol wasn't working. went back to the doc on tuesday they did no u/s just asked how i had been feeling and assumed i was miscarrying. drew more blood and they said my hcg levels halved. i don't know why but i have a feeling the dr is wrong and i'm not miscarrying. i hadn't really had pregnancy symptoms so i can't say i don't "feel" pregnant anymore. but i hadn't passed any tissue that i know of. doc also told me the hcg levels could go back up as well. i'm so lost right now. we'd been trying for about 3 months now.