13 dpo and period is due tomorrow.

I've been dizzy and gassy all week and spotting yesterday and today. We BD in the days before and on the day of ovulation for certain (positive OPK and had ovulation twinges).

Could this be implantation bleeding do you think? I've read not everyone gets it so I might just have my hopes way up. Negative tests so far but thought I saw a super faint line last night in the right lighting.

Am I testing too early? When should you normally expect to see a positive if you're pregnant?