Confused, 19 days late, had a small clot and pink spotting

So I’ve been with my partner four years..

And This is the first time I’ve been this late in a long time (last time I was pregnant and then had a miscarriage).

I’m 19 days late with symptoms—two negative tests one slight positive test, followed by a negative.

I had sharp cramps that lasted a few minutes prior to having a small blood clot and mild pink spotting.

I haven’t bled since then, and I’m not sure if maybe it’s late implantation?

I have an obgyn appointment on the 17th but I wasn’t sure if anyone of you have experienced this or had any advice?