What Causes Delayed Period While On Biotin?

I have been taking biotin on and off for about a month now. I have also been off birth control for about 3 months. My period was 10 days late last month but 2 pregnancy tests came out negative about not even 2 weeks ago i took another one it came out negtive. My period is already 12 days late i have taken 3 pregnancy test yesterday 2 of the clear blue and 1 dollar store and they all came out positive am i pregnant or can the biotin be doing this to me?