I am never late always on time. I'm in my mid 30's and trying to conceive. I was supposed to start my cycle on Monday,which never came (hoping I was pregnant). Late Tuesday I had to go to bathroom and felt a small mass pass with blood. I haven't had anything else since then and don't know if I miscarried or super late.

A few days late is not "super late" even a week is not "super late" for many women being late one week or so, is more normal.

While it is possible, it can also be many other things.

A very early pregnancy would not create 'a small mass'. Miscarrying at that point would be hardly noticeable. I suggest though that you get checked out. It is impossible to diagnose or even ascertain on the Internet.