Do what you feel is right. If the time is right to wean then do so...if you feel you'd like to continue then do so. Don't let anyone make you feel guilty about stopping or continuing. That's number one.
If you are ready to wean, make sure you're down to 1 feeding per day, if you're not, you'll want to eliminate 1 feeding/day, once a week. so if you're still nursing 3x/day, you'll go to 2 for a week (or more, if you're still engourged), then 1, then none, each week till you're done. listen to your body and if it takes more time, then so be it. with my first child I had mastitis a lot because I tried to go too fast. It ended up taking me months longer.
Once you're down to the 1 feeding, mine was at night/early morning w/both kids (mainly because I liked to sleep in lol), you can just stop. Both of my kids threw some night time tantrums briefly, lasted about 1 week. I just kept saying, I'm sorry, mommy doesn't have any milk left to give you over and over again. Milk is allll gone. ;) Again, after 1 week or less of sticking to my guns, they got over it and all was forgotten. Oh, I weaned my first child at 11mos (because I needed to get PG again soon due to my age) and weaned my 2nd child at 19mos.
Regarding the milk/soy intolerance. Our house is entirely soy, no milk products. 1/2 the family has issues with it so I don't buy it. There's plenty of rice based options you can try. Some are quite tasty, and remember, she doesn't know what "milk" really tastes like so what may not taste "like milk" to you, may be totally acceptable to her. :) Like many others have said, milk is not a requirement in the diet and there are MANY more suitable options out there.
I think I'd also give the NAET/Accupuncture a try for the milk/soy issues. I have gone to an accupunture/chinese medicine dr in the past and had great results with that. It did wear off for me and I'm back to having major issues with milk so I need to go back soon! I've also got several friends that take their kids to a chiro/accupuncture/NAET dr for everything but their yearly checkups now. The regular drs don't do anything for illnesses usually but the chiro usually fixes them up within 24-48hrs with an assortment of treatment options. I'm planning to take my kids there next time they get sick.