any suggestions?

I thought I saw a vvvfl on 2 tests a week before AF (8dpo then 11dpo), then a neg FRER (14dpo). started bleeding 15dpo (today) BUT it's very light and bright red/brown (mainly bright red). my periods are always really heavy in the beginning with signs its coming and not this bright color, and this time it was a surprise with absolutely no sign at all (no bloating or different body/vaginal smell or headache all of which happens within 5 days of starting). I usually pass a lot of clots the first 3 days but I've only passed 1 small one. my SO and I as well as friends were so sure I was pregnant based on how I had been feeling and the changes my SO noticed with my body. should I just assume this is AF and keep trying? I am currently taking 5mg letrozole during my cycles because we are TTC and I do not ovulate without it. my SO wants me to call my doctor in the morning but I'm not sure what my.doctor will say. should I just assume i am out, and refill my letrozole and start taking it on cd3 as planned, like always? ***UPDATE*** so the first day (yesterday) was bright red. today (second day) is now brown. what is going on? I've never had this before. I'm thinking a MC, my SO did some googling and we think that's what is happening.