Dietary change- late period?

So in the last month I've decided to cut out most animal products. I haven't eaten meat in about a month and consume very very minimal dairy, if any at all. I am coming from a diet pretty heavily focused on meat and dairy, so it is a change in my diet. I'm on the pill and the past 4 months I've been bleeding a little on the 3rd week of my active pills and then I'd have a period during my sugar pills. However this month I didn't bleed at all during my active pills and now it's my second day of sugar pills and I am still not bleeding. I am sexually active and we don't use condoms however my boyfriend always pulls out. I've also never missed a pill or even been late for a pill. I'm just nervous I could be pregnant since I've been used to bleeding the week before my sugar pills and the week of my sugar pills and now tomorrow is my third day of sugar pills and still no period.