Oh dear :-( sorry it's been such a hard road for you.
You've tried so hard at this, but I'm left with the feeling if I'm honest, that if you carry on, I think you'll be doing it more because you don't want to feel that you've 'failed' at it, than because it's the best thing for your child and your family.
Being in pain at every feed will affect the bond you have with your child. What should be an enjoyable part of the day becomes one where your child sees you wince in pain, and likely dread each feed. That's not good for either of you, and not good for your relationship with each other.
Ask yourself why you want to continue? Is it for health reasons - if so, that's fine, but make sure you are clued up on which benefits are real and which ones are not. From my reading of the research, I came to the conclusion that there is very little in the way of compelling evidence that it will cause any significant benefit. That doesn't mean it's not good that you've done it so far, but that if you carry on, you need to know the score, or it's hideously unfair to you.
If it's for bonding reasons, even if there is any evidence of this (which tbh I don't know) then your situation and the pain you find yourself in is likely to counteract that. Also, don't underestimate the bonding value of your child being able to look you directly in the eye whilst feeding, which you get with bottles.
And if there are any benefits, then you've done it for 3 months anyway.
You are putting yourself through hell that is completely unnecessary for the health and development of your child. Your child will grow equally well on either milk or formula. Your child would probably benefit more from a happy mum right now, and you need to do whatever it takes to make that happen. So continue if you want, but be very clear to yourself as to why you are doing it.
Boob is great if it's something you want to do and that you and your baby are thriving on.
Given where you are now, I think you have 4 options personally.
-continue, but accept that it's going to cause you pain. It might be that you are ok to live with that, and it's your choice to do so.
- move entirely on to formula.
- exclusively express, if that causes less pain
- do mixed feeding, in some combination.
Good luck