When can i start ignoring a negative home pregnancy test?

i got a period both january and february i had unprotected sex the day after my period ended which was february 17th nd the month after which was march 7th it's now june and i've still haven gotten my period. i've taken 4 home pregnancy test and all came out negative. i've been having headaches, backaches like crazy, i've been sleeping alot, i felt fluttering in my lower abdomen 4 times, alot of discharging, i even have the black line on my stomach, but no morning sickness. i'm a big girl and i've always had stomach but it looks like it has gotten bigger and a lil harder...could i still be pregnant even though the hpts coming out negative???