Help!

This is my first month TTC, I just got married and we just started trying. I am always very regular and on a 28 day cycle. Right now I am 1 week late and very nauseous but I took 5 HPT and all are negative. 3 I think I took way to early just cause I was excited but the last 2 I just took. I'm just confused because I've never been this late before and don't know what to do!  Any advice is greatly appreciated, since I'm new to this!