Prenatal and Irregular Cycle

I've been ttc since January, but i have irregular cycles and haven't gotten pregnant. I have read a lot about women taking prenatal vitamins to help get pregnant.

I started taking them about 2 weeks ago, and my irregular cycle took a weird turn.

My cycle is usually very short, but I'm on CD 28 and have no signs of AF. (Three negative tests) If you look at the cycle chart i posted, you can tell how weird that is for me.

Could my cycle be getting longer/more regular due to me taking prenatal vitamins?