I know you talked to some experts, but have you been to see someone recently about this issue? What may have seemed normal early on as far as latch and baby’s behavior may be looked at in a different light at two months of age. Can you see an IBCLC who is clinically trained and experienced in outside the norm breastfeeding problems and can take some time with you and watch baby nurse, examine baby, etc? like this - http://cwgenna.com/lconsult.html
Has reflux and/or forceful letdown been ruled out in your opinion? Has baby been examined for tongue or lip tie?
Because otherwise I am truly confused about what would make your baby be so unhappy while nursing all the time and all this time. Feeding at the breast is the normal way for all babies to eat, so if a baby is unhappy nursing, something is clearly not right, so its important to figure out what it is. While I think our support can help, this is starting to sound to me like it is outside the normal course of breastfeeding that LLL Leaders and CLE’s (breastfeeding educators who give classes) are usually going to have much experience with. This is why there are IBCLC’s- to help mothers and babies with outside of the norm breastfeeding issues like this.
Also, let's say your baby simply is unhappy nursing and there is nothing to be done but bottle feeding. I think this is unlikely but, you have been living this for 2+ months, not me.
Is pumping & giving your baby your expressed milk an option you would consider? This would have two benefits-1) your baby would still be getting your milk, and your milk production would be there should you and/or baby wish to try nursing again down the line. I cannot tell you how many moms I have talked to who stopped nursing in the early months who regretted that decision later. Too many. So if you have any doubts on that score, I do suggest consider trying a little longer or pumping to keep up your production if you switch to bottles.