Not sure what all this is...need advice

So I was due for AF on Sunday February 2. My app predicted I would ovulate Jan 20th. My last period started Dec 27th and I have been off bc since August. Since that time it's been 37-38 days regularly. This our first official month ttc. I thought I was having lots of symptoms the first week then they just went away. I last tested Tuesday feb. 4 and got a bfn. Still no af  on Feb 7 and today I've been cramping, tired and unfocused and sick to my stomach twice as well as nose runny. Should I test again, if so when? I had pretty much decided it wasn't going to happen this month but now I'm not sure. I don't want to keep wasting tests. How late do you go see your dr to see what's up if you keep getting bfn?