Sarah, I'm knock-kneed, over-pronate (so much so that I ruptured a tendon, just by being flat-footed), have had years of netball-caused injuries, am old and ugly, was told that I should give up running and I'm doing my first HM on Sunday.
Don't give up, if I can do it and I'm a lot older than you (
), then I'm sure you can. I do exercise to strengthen weak muscles, stretching to loosen tight muscles and Pilates for core strength. I wear orthotics all the time because I need to.
I started slowly and am taking it easy. I'm now seriously considering going the full hog and training for a marathon. If/when I do, it will be slowly, but I'd rather get there slowly than not at all.
You might need to wear orthotics - as Cake says, try local running clubs for recommendations to physios and podiatrists who work with runners - they'll understand you better and will work with you to get you running.
Good luck