Am I Gonna Miscarry?

I am currently 13 weeks & 5 days pregnant with a boy. He’s my rainbow baby as Ive had a miscarriage 2 years ago with my first pregnancy. Ive made it past how far along I was with my last baby but something weird has been going on & Im not sure it’s normal? I just recently had my first bacterial infection & last night I took my last pill antibiotic for it. Well the past Id say maybe few weeks Ive had this real watery discharge with what looks like tissue pieces in it. The first few days, the pieces were fairly small. Now I noticed 2 days ago that the pieces are getting even bigger. Like big enough to cover half my thumb nail if I spread it out. It literally looks like sheets of toilet paper. My discharge is also a little yellow. Im guessing this is due to the antibiotics I was just on because of the bacterial infection. My Dr did ALL std tests & tested me for EVERYTHING & all results were negative. I read something online saying my endometrial lining is maybe shedding? Can that cause me to miscarry? Is this a early sign of a miscarriage coming, cause Im honestly scared. 😔 I dont wanna lose this baby too. & Please dont tell me to talk with my Dr because I already have & I feel like shes not really listening to me or taking my concerns seriously.