Well done for trying your best to deal with your anorexia, OCD and other issues.
You say that they have long since been a problem, and haven’t caused you upset for some time, so you dealt with them as best you could.
Having had these issues you can probably understand in yourself that you have the potential to be prone to deep feelings and anxieties. We can deal with our issues but I’m sure you’d agree that the potential for them to become problems at a later stage in life is still there.
Could it be that this recent change in circumstance, a seemingly life changing one, considering the fact that you’ve not been in a relationship before, has reawakened some anxiety, has bumped your life as it were and possibly made you feel vulnerable?
Certainly loving someone and needing them can make us feel this way. And knowing that you need someone can cause terrible fear in all of us, fear of loss and hurt?

Anyway, just my thoughts, I apologise if I said the wrong thing but I do hope you can cope with these demons you’re facing,

FF