My GP was worried when I got to 6 weeks, surprised when I got to 8 weeks and simply astounded when I got to 11!

You've gone 10 weeks without AF, definitely worth starting the ball rolling and getting things looked at. You may find a GP isn't too bothered and will tell you to just wait, but ask for a referral to a gynecologist anyway. Specialists are usually much more willing to look into the reasons behind it.

BW