Confused and a little frustrated

3 months ago I got my first birth control shot in the first week of December I was suppose to go get the 2nd shot but I didn't . So the second week I got my period again(my period always come the 2nd week in the month) but now it's the 3rd week in January and as of today I'm 10days late in my period. The only thing I noticed that's different is I'm always tired(I sit at a desk all day) and my boobs itch a lot. I guess what I'm trying to ask should I take a pregnancy test or just wait to see if I get a period next month? Any feedback will help plz and thank you