Feeling discouraged 😔

I am 15dpo and took a pregnancy test and no positive.. this is my 1st cycle on Letrazole 2.5mg and everything seemed great until today I went to the restroom and wiped and saw brown discharge and felt cramping. I am 2 days late for period and been having alot of pregnancy symptoms....I wanted to wait till Monday to test as my doctor advised but decided to take first response pregnancy test. I have no hope that it could still be a positive. Has anyone had a positive later then 15dpo? I dont know what else to do...I have that debate with my husband that he needs to get his semen tested looks like he will have to now..