My girlfriend is suffering from something that sounds quite similar to many of your problems, so I've been trying to find out more about her symptoms in advance of her appointment with a specialist in a couple of month's time.
I'm definitely not a doctor, but one thing that keeps appearing in my research is Lichen Sclerosus. This disease is commonly mis-diagnosed as thrush so it can go untreated for a long time... and the longer it goes undiagnosed, the greater the chances of the cuts leading to scarring.
A diagnosis often requires a biopsy, but some of the articles say that an experienced skin specialist should be able to tell just by looking... so I decided to see if there were any images on google. Most of them are for quite extreme symptoms, and look a bit scary, but some of them show more minor symptoms so I thought it could be helpful if I send you the links. As someone said above, printing out this information and showing it to your doctor could help speed up diagnosis so I hope this information is useful to somebody.
The best advice from all sources seems to be to abstain from penetrative sex (or at least, vaginal sex) until the condition is fully treated in order to avoid the tears which can lead to scaring and reducing the size of the vaginal opening. If you catch it early, it seems the steroids can be extremely effective. If scarring has occurred, it may be necessary to additionally use vaginal dilators (or surgery) before you can return to having sex as before.