Long cycle, what’s the deal?

Sooooo I’m currently at CD 35. I️ usually have 28-30 day cycles, so when I️ got to the day when my period was expected and my pregnancy test was negative, I️ assumed I️ wasn’t pregnant. However this month I️ did not do OPKs, I️ was really busy, so I don’t know when I️ ovulated. I️ was at a work conference the last two days, and I️ didn’t pack pregnancy tests because o really expected to get my period while I️ was there, but it’s still MIA. I’m going to take a pregnancy test again tomorrow morning, but if it’s negative, what could be going on???