I have policistic overies and I have irregular periods normally

Pregnancy is fairly unlikely because of the polycystic ovary syndrome. Having periods every 3-4 months means that you only ovulate 3-4 times a year at the most.
It's true that the norethisterone does not work as birth control; it just brings on a period. However, as long as your period comes, that's good evidence that you're not pregnant.
Since you took the last pill on Friday, I would expect you to get a period Sunday or Monday (2-3 days later). As long as the period comes, that means that you're not pregnant.
Just in case your period doesn't come, then I would do a pregnancy test. I would wait about 14 days from the first day you had sex so that it will be more reliable if it's negative.
Most likely your period will come today or tomorrow. If not, then pregnancy is possible.
In the future, using condoms or something for birth control would be wise. You're not very fertile because you only ovulate 3-4 times a year, but if you happen to have sex near one of those days, then you could end up pregnant. Best wishes.