Miscarriage

Just a general question about miscarriage. I had a positive test 13dpo, and had been having implantation bleeding, which did stop after 4 days. On 18dpo I began to bleed heavily, I will be getting blood work drawn tomorrow, but the past 3 days my flow has been very heavy, with tissue and clots, general cramps. Not much worse than normal cycle discomfort... my doctor had me take another urine pregnancy test today... it was still positive... what would you consider this? A chemical pregnancy, a miscarriage, do I need to worry about this being an ectopic pregnancy? The pregnancy test was very faint, no darker than it was before... but also no lighter. Any insight would be great. 😔