Blood test ? Need advice....

So my feet are starting to swell up& like a few days back I got extremely nauseous and had a headache the whole day...I went camping for 4th of July and was on my AF but had none of the usual symptoms. And it wasn't heavy, my aunt told me she had her "AF" for 3 months before getting a blood test to find out she was pregnant & then at work my boss told me another employee had her AF for 3 months till she found out.. idk, I wanna get a blood test but the BFNs just keep hurting me & I don't wanna like get all excited (because my so is like super into all the myths & believes i am). Need advice 😣.