Can You Be Pregnant And Not Know??

Hello Ladies, Thought I would as on here, as you will know much more than me. 

2 Years we have been trying for a baby. 

Basically I started my period on 15th-16th Of September, 3 days cycle(normal for me) bleed was fine(I l I think it was) 

I then had my next period on 17th Of October but since the September period i have been feeling it myself at all, this is what's happening 

-Bloating-Like my stomach is turning(this hasn't stopped since then) 

-Forgetting Things Easy

-Headaces

-My Last Period Hurt So Bad(Normally I don't get them this bad) 

-Had a lot of wind

-Diarahha(Going more often) 

I'm now waiting for my November period which not due till 17th my cycle is every 31 days, me and my partner have sex it every other day, but for 1 weeks now my nipples have been sore and more out than usual, I have taken pregnancy test in september and took another in October both negative but I have read up a lot of research on being pregnant without knowing, so I am really looking to see what you suggest to do as I feel different and bloating won't go(stomach Feels more bigger than usua) 

thank you