Pregnancy possible?

So I need some advice.. judging from the below cycle calendar I’m guessing I ovulated around the 21st December (I got lazy measuring over Xmas so the app didn’t track it but judging from when my period started I’d assume around then?)...

Me and my SO BDd on the 26th. Is it possible we conceived? I had a very short and light period on the 2nd Jan.

I took a pregs test on the Monday after my period and got BFN. Did I test too soon?

I’ve had loads of pregs symptoms this month: nightmares, fatigue like CRAZY, dizzy, really crazy strong nails, mood swings and tonight I threw up after dinner which I never do!

After having the period and a BFN, is there still a chance I could be pregs? I don’t want to waste a test if there’s not really a chance!

Someone help haha