I need opinions

Hey! So I’m 21, just moved out on my own WHOOP WHOOP! However that means a lot of sex with my boyfriend.

I’m not on any birth control, we use condoms with pulling out and inspect the condoms thoroughly before & after.

I am now 6 days late for my period and I’ve been kind of freaking out, but 6 pregnancy tests later and they all say negative. However, this is my first cycle after moving, I’m a CNA who switches between night and day shifts frequently over the past month, & I guess this cycle I’d say I was stressed out. I also started an anti anxiety med!

My periods are never the same but 6 days is pretty excessive even for me.

Any thoughts? Is it more than likely stress and I should stop stressing?