Could these be early pregnancy signs?

They can actually be symptoms of both your period and pregnancy. I would think that if you were going to have symptoms from the pill they would have happened a week ago when you took it. Theres really nothing you can do now, but wait. If you dont get your period, or do and it happens to be way lighter then normal, then I would get a test. Otherswise, just hang out, and try not to stress because that can delay your period as well. Good luck!