Implantation bleeding ?

I’m on progesterone because i have a short luteal phase and when taking it you don’t typically bleed as it builds the uterine wall. I started spotting 3 days ago pretty red but very light. Today it is barely there and is now a brown discharge. Took a pregnancy test and it shows pregnant. Doctor had me Go in for blood test to check hcg levels and I go back on Saturday to see if they doubled. Not getting my hopes up yet... as I’m thinking this may not be a viable pregnancy due to the spotting.

Has anyone ever experienced this before ?