Hi elevated, I'd say that you never can tell how long it's going to take to move on from someone as every relationship and every person is different. And it sounds like you had a really deep emotional investment in this relationship.
Some people say that some breakups can have the same effect as a bereavement and the same/a similar grieving process, and obviously the bereavement process can take a long time to pass through.
I, just like you (!!), would like to see you moving past things a little more easily though. Do you think it might help looking at the ending of the relationship again, with slightly different perspective, to give yourself a little more closure? Maybe it would help you in writing down all the things you're feeling? Maybe you could talk to your therapist for some more support- even edging on grief counseling?
For some people, getting out and meeting new/different people can help a bit in moving on, but that part must be really difficult for you having a social phobia and/or finding it hard to get out, so it is really understandable if the moving on bit is slowed down a bit for you. But perhaps just talking a bit more can help speed things up for you?? Whether that's here or/and with your therapist.......
Alison