still late on my longest cycle!

Natasha
I'm new here (started using Glow roughly 3 weeks ago) and I could really use some help. Please bear with me as I haven't got all the lingo down and I do tend to ramble on :$ Myself and my DF have been ttc #2 for 3 years and essentially 'gave up' a couple of months ago. I've been irregular since having DD and af typically visits around CD37 (but can be as late as CD50), so anywhere around 5-7 weeks. Now, I've had strong pregnancy symptoms for the last 2-3 weeks (including darkening of the areola? and being so nauseous that I've been sick) along with other unpleasant things. I got bfn with fmu on CD45 (1st July) and again on CD51 (7th July), there's still no sign of af and I still feel pregnant... am I just going mad and clutching at straws? Has anyone with irregular cycles had false bfn's?