Bfp but sad.

On Monday 9/16.. I got a faint bfp at 10dpo. I was scared but happy as we have 4 already and my husband said hard hard no to more. Well, oops. The line got slowly darker until 13dpo, then started getting lighter. Today, Saturday 9/21 is 15dpo and FMU test was light. I had some bleeding today (see pics). Do the FRER tests tests look bad? They are from today, 15dpo. All my other babies' tests were DARK by 15dpo so I am super worried. I've never seen tests so light. Does the bleeding look like the start of a mc? I had a beta drawn yesterday and I am still waiting, then have draw 2 on Monday (17dpo). Please mamas... did anyone have this situation and it ended up ok? I need anything I can get. I didn't know I wanted another baby and now I feel desperate!