Should I start my new month of birth control?

Hello!

I am 21 year old who has been on and off the pill since I was 16. I'm very bad at remembering to pick up my birth control and since I'm not sexually active I don't always start a new pack right away (I know that it's bad). I skipped one for like a month and half but didn't get my period at the end of that month like I probably should've. Now it's my off week (sugar pill week) and I'm suppose to start my new pack on Friday (it is now late Wednesday) but I still haven't gotten my period. My stomach feels sort of hard and I'm a bit concerned it's connected to my no periods. I am planing on going to the doctor for a flu shot soon so hopefully will question those concerns if still present.

Has anyone had any similar issues or heard of things like this?

Also it is 100% impossible for me to be pregnant. I haven't been in involved with any sexual activities in my life.