i need advice!

k so if anyone saw my post earlier about being sick for a week, i went to the doctors today. apparently i have strep throat. 2/3 things they gave me are %100 safe while pregnant. the last one (cotridin) should be avoided during the first trimester of pregnancy but its for the congestion im having that makes it difficult to breathe. now i got my tubes opened on cd5 this cycle. and just have this gut feeling that i could get my bfp this month. but af is not due till thursday-saturday this week. (most likely Friday but its always within the 3 day span) i have a FRER sitting in my bathroom and i wanna take it asap so i know if im okay to take my medicine. do you ladies think i could get a decently accurate result if i test tmr with fmu? id be roughly 11-13 dpo tomorrow according to my apps estimate. and i know i should wait till af is late for best results. but like i said this congestion makes it difficult to breathe so id like to start taking my medicine for it asap, or see if they can give me something else. or would it even affect the baby if im pregnant this early on? any advice would be great!