Amusement / theme park

Ladies... I am 18DPO and still getting negatives with no sign what so ever of AF showing her ugly head. 
I have a little bloating and a little Pinching sometimes but nothing really. I'm getting negatives tests. 
I'm supposed to go to an amusement / theme park on Sunday for a day out with my big brother, we have never spent the day together just the two of us before, normally the rest of our family's would come so I'm super excited.
 
I just don't know what to do in case I am pregnant but it's just not showing on tests yet, any advice would be appreciated.