Ankle sprain- 12 weeks to heal?

Hi all,

I sprained my ankle in a fall around 12 weeks ago, and I�m still suffering quite a lot of pain. I had an X-ray at the time So i know nothing was broken or fractured, and I did everything that I was told- ice, rest, elevation, trying to walk when possible so as it didn�t stiffen up (obviously without over-exerting it), but it still becomes extremely painful if I do something as simple as step on a stone in the street. It isn�t as swollen as it was when it first happened, but it does still swell slightly. I�ve been wearing flat, supportive boots or shoes since it happened, cannot even put my Foot in anything with the slightest heel, and am getting a bit frustrated at the length of time it is taking to heal. Is it normal for it to take this long?

thanks
1st of all it should have been immobilized for 3 weeks. The new plastic casts.
after which therapy should be scheduled.