Do another test tomorrow with your first morning urine as it will be more concentrated. If it still is negative and you continue to get the same symptoms after AF has gone then see a doctor and ask for a blood test just to make sure.

Testing at night is not a good idea as it often wont show as it's not concentrated enough. How often are you you urinating and how much are you drinking? I ask this because I googled this yesterday and I found that diluted wee (from drinking heaps) or wee that hasn't been in your bladder for long (due to frequent urination) can cause a false negative. This can be a problem for ladies who get early symptoms.

The reason I googled it is that I've been going heaps myself (and had other symptoms) and tested on CD24 (yesterday) and got a negative. I will not test again unless my AF doesn't arrive by CD28. I'm pretty sure my AF is on her way now though as I've started to spot.