This will get complicated... Please bear with me...

I've been on the pill for about 6 months. Two weeks ago (The friday) I took the last pill, and went on my period week. However I was on holiday and had forgotten to take my new pack of pills to start the following week!
.. I had sex on the Sunday (One day after I should have started the new pack)
.. Is there more chance I'm pregnant? Should I see doc or get test? Or was the last pack still quite effective as it was only one day late?

Sorry forgot to add I'm 21

Slight increase in the chance, but still unlikely since it was just the one day. If it were to happen again, you can take two the next day when you remember. If you miss too many in a row, however, it is better to use another form of birth control and start over with a new pack when you normally would have started one had you not missed any.

Continue taking your pills as directed and see what happens when you would expect your next period.

But all the pills and websites say strongly that you shouldn't take two in one day if you forget

but all the pills and websites say strongly that you shouldnt take two in one day if you forget This is true IF you miss constently. Just doubling up once or twice shouldn't be a problem, but don't make it a habit. One warning though, doubling up like this could make your stomach very upset.