A little long but please read is this even possible?!?!

So ladies. Hubby and i have been ttc for about 6 months now. My last period started on july 4th and ended on the 10th.i went on vacation july 6th to july 24th. When i got back on the 24th hubby and i had unprotected sex that night and for the next 2 weeks. About 2 weeks ago i had spotting. A couple wipes if blood for 2 days then it stopped. My period was due August 7th its now the 20th and im late by 13 days. I have been having short and random nausea spells im alot tired i cry over alot of stupid things my lower back is hurting so bad i cant bend over too far and iv had cramps this past week but there barely hurting and they dont last for long either about 5 10 minutes.i havent had any yesterday but had some cramping this morning but it was barely there. I took a test this past thursday but it came out negative. Could i have tested to early? Could i still actually be pregnant?