When I share fears like this with my therapist, that I'm very shy, I don't do many social things, and I'm terrified of being not enough for a man, she says, ' When it comes to fear, you just have to do it' ..but that doesn't help all that much really. I need to get to changing the perception I have of myself. I need her to also help challenge my negative inner voice.

I'd say just take little steps towards meeting someone. The right one won't mind if you are reclusive sometimes. I'm going to try to join some type of club to meet up with people maybe once a month just to challenge my own mind.

I don't think your age or mental health is so much the issue as is the reclusivity, unless the other you're hoping for is also a recluse.
Which in itself creates a dilemma - if you dont get out, you dont meet people to get close to, to bond with to become someones special someone.

Well I see a huge contradiction in your situation.
Maybe this can help you out a bit.

Your comfortable being isolated.
No problem.
The only thing with isolation is, it is hard to meet woman that aren't around.

So, if you want to meet a woman you need to go where woman are.

You could like designate one day a week to not isolating and go where woman go.

Then you would kind of be able to do both.

Being "reclusive" isn't the problem. Being that way and then expecting everyone ELSE to come to help when something happens with no reciprocity- THAT could be the problem.

I have sometimes thought of life as being like a cat. If you sit quietly for a while, often the cat comes to you.