Richard said a lot that I was thinking as I read your post. It probably is time to either have your pouch removed, like he is doing, or to have it diverted to a permanent ileostomy, like I recently did.
I think you have grown up while your friends and fiancé have not kept pace with you. You are too young to settle. You need to find your purpose and get on with living. Break ups are difficult. We just celebrated our 40th wedding anniversary and last year at this time we were discussing permanent separation. I understand your loneliness. You can feel really alone despite living with someone. Please don't sell yourself short. You deserve to have as full of life as you want.
When you have a partner you should be able to discuss how the financial resources are used. It doesn't matter who brings in the income. Usually both partners make different amounts and there is trouble when the one making the most thinks they can dictate or rule all.
You self esteem is there. You know you need to make changes. I don't mean to pack up and walk out tomorrow. Hopefully you can make a list of life goals. Go to the library and check out a few self help books......they are free.Money is tight so I suggest you find counselling somewhere affordable. For example you might be able to call your local United Way for help locating a therapist. Some non profits offer counselling on a sliding fee basis.
It is good that you got it out by posting here. There are lots of resources on the internet.
Take care of yourself. You have a lifetime to design.