Advice

I'm suppose to get af on May 13th..I'm 9 dpo. Yesterday my mom looked at me a said "You're pregnant" I asked her how she knew she said " I just do" I decide to take a hpt this morning and I got a bfn. I told her that and she said "Those tests lie, you're pregnant". I'm undecided whether to believe my dollar store pregnancy test or to go purchase a first response. I know it sounds crazy that I trust my mom's words over the test but I've been ttc for over 7 yrs. What would you recommend I do?