I think Alan is spot on here. Time for a reset on your approach. Based on the symptoms/pain you describe, it sounds like your OCD is still there, possibly worse than it was pre-surgery.
A few thoughts as follows (quick disclaimer - this is based on the experience I went through, and is not necessarily all going to apply for you; I think you'll be able to judge what might be relevant for you, and/or also give you some ideas on things to discuss with your doctor on your next visit).
1. I'd be surprised if the Ostenil injection improves anything. Ostenil is a brand name for hyaluronic acid - think of this as a lubricant that is injected into your joint to supplement the synovial fluid (your body's natural joint fluid). This is a treatment that is most commonly used to treat symptoms of osteoarthritis - not OCDs. I got an injection of Synvisc (another brand name for hyaluronic acid) and it did nothing for my OCD. Your problem most likely that your OCD is still present, not general joint deterioration like osteoarthritis (this would be unusual for someone your age).
2. Get a copy (or better still, multiple copies) of the MRI images and radiologist report from the facility that did your MRI. The facility should be able to give you a CD (or several) with the images on there. Bring these MRI images to other surgeons like Alan suggests - to get a 2nd, 3rd, 4th opinion. This will help speed up the process, instead of these surgeons ordering their own MRI images.
3. For your next opinion(s), it really pays to see a surgeon who has a lot of experience with OCDs. This is probably the hardest part to figure out - which surgeon to go to, and if you'll be able to get to see them (based on their schedule, your health care coverage/insurance, etc.). In the US there are a number of surgeons people on this forum have recommended. Unfortunately I don't know much about surgeons in the UK - possible others on this forum do.
4. Between now and when you get your next opinion(s), the most important thing is to do no further damage to your ankle. Use pain to be your guide here - if it hurts a lot, you are likely doing more damage. If you have one, wear a rigid walking boot for getting around - this may even allow you to walk without crutches. But if you need to use the crutches also, use them too. I found that Blesdoe makes a rigid boot that's easy to walk in (
http://www.bledsoebrace.com/products/lo-top-boot/). I'm sure you can order online from somewhere in the UK. Until you get you next opinion(s), I'd be very cautions about doing any physical therapy or rehab. If your OCD is still present, rehab will likely not help.
5. When you mention a carbon fiber orthoses, there are a few things that your doctor may have been thinking of. Most likely, insoles that tilt your foot in a direction so as to alleviate the pressure on your OCD. These can be helpful. I wear them every day.
6. If more surgery is required, its possible that microfracture by a skilled, knowledgeable surgeon will work. Also ask about denovo, and biocartilage. OATS is an older technique that is still used, however usually only if the several other of the former techniques have not worked.
I hope this helps. Best of luck with things!
Dave