Could I be pregnant?

Okay ladies, so I had sex with my SO on my birthday (September 27th) we used protection but after taking a break we did a quick round without protection I'm not on any birth control or anything. I got my period at the beginning of this month but recently I've been feeling really tired. Today I was rocking my baby sister to sleep && I closed my eyes && nearly fell over by his dizzy I was. I also feel very bloated? Could I be pregnant or just overthinking it? I plan to take a pregnancy test tomorrow.