Missed and late period

Hey my period came February 19 and lasted for 5 days which is normal then i went missing for March and April. It came May 2nd lasted for 5days then the 20 of May and lasted for 3 days.  It came june 19 lasted for the normals 5 days. On the 15 of july i had spottings only when i wipe i see it lasted for a day i took several pregnancy test but my period was due yet the 19 of july came and my period was MIA i took pregnancy tests again even in the morning when i get up my brrast nipple are big now usual i have no breast nipple only when it's been play with i've been going tl the bathroom alot now mh period is 28 days late i'm a bit worried now.. I'm 17 by the way and i had sex couple time in june when my period tracker said i was ovulating... Please help me