I suggest trying Nature's One Toddler drink (its is a powder like formula). My vegan friend gave this to her daughter (adopted) until she was 3 or so, and I trust her. Its almost vegan (there is vitamin D in it). Its as close as you can get to vegan milk for kids.
Neither of my kids like Hemp Milk, but I wish they did, because my HFS had it for 99 cents and I bought a ton. I don't think I even liked this last batch.

The fat that they need does not necessarily need to be in the milk they drink. You can always add flax oil, Udos, ground flax seed, coconut oil, or other oils to their food. That's what I do, so then I don't really worry about what kind of non-dairy milk the baby drinks. He only has about 3 ounces a day (small glass with lunch). I give him coconut milk, rice milk, almond, soy, etc......whatever is open in the fridge! Mine still nurses about 3 times  a day too.
Don't cows have hormones in their milk (designed for the calves) even if its organic (no extra hormones added?). I'd be more worried about that than the hormones in soy. All veggie foods have estrogen in them, I believe.

RIght, like why is nobody worried about the estrogen in broccoli? Or spinach?
Soy has gotten a bad rap because it is known as a meat/milk replacer.

This was in my email this morning. Not totally related, and I don't think Coke is a great beverage or anything, but I would drink it over milk:

Things go better with Coca Cola, things go
better with Coke. Life is much more fun when
you're refreshed and Coke refreshes you best..."
- Coca Cola Theme Song

http://www.youtube.com/watch?v=wW-uH4u6ikc

**************************

The October, 2009 issue of the British Journal of
Nutrition (Br J Nutr. 2009 Oct;102(7):1047-51)
analyzed insulin-like growth factor-I (IGF-I) blood
serum levels in young men between the ages of 22
and 29 who drank 2.5 liters of milk for 10 days
and then drank 2.5 liters of Coca Cola for ten days
(with a ten day rest period in between trials) and
concluded:

"A decrease in serum IGF-I was observed in the
cola period compared with the milk period."

**************************

Milk drinkers have higher levels of IGF-I?
That's no surprise to Notmilk readers.

IGF-I has been identified as a key factor in the
growth and proliferation of every human cancer.

IGF-I is identical in human and cow so that when
humans drink cow's milk they multiply the level
of IGF-I in their bodies.

I don't support them, and don't drink Coke. :)
The point of the article by Robert Cohen was to show that Coke is healthier than Milk. And we know Coke ain't healthy! ;)

I'm throwing in my two cents.  I don't think those alternative milks have enough protein compared with soymilk.  Edensoy Extra (which is fortified) has something like 11 grams per protein per cup.  One year to two year old toddlers don't eat that much solid food--their tummies are very tiny--and I found the soymilk to be an invaluable way to ensure they got sufficient nutrition. 

I think hemp milk has more protein, but my daughter spits it out, and honestly I don't blame her...it has this aftertaste...ugh...I wish we liked it, maybe its an acquired taste :) My co-op has started offering coconut milk, (by So Delicious I think) which I'm sure is tasty, has fat and maybe a couple grams more protein than rice milk...(my daughter was allergic to soy before, but now that its better she has soy milk sometimes. I do like that theres more protein in there.

I looked at this when my daughter was the same age and I thought I was drying up. 

http://www.naturesone.com/soy/

It was vegan then, and I believe it still is.  The ingredients list vitamin D3.  At least it doesn't contain corn syrup.  I just feel that a child that young isn't ready to make the switch for BM/formula to "milk." 

Have you tried using fenugreek?  If you decide to go that route, make sure to read instruction online and not just the ones on the package.  There is even a prescription drug that can be used if you're desperate.  You will need to pump regularly to get you supply back up though.  I was in the same situation at one point, and ended up able to nurse until my daugter selfweened at the age of 3.  I'm not condeming you if you chose to go another route, but I just want to encourage you that you do have options that you may not have yet considered.  She even went through a phase when I quit my outside job where she wouldn't eat many solids and only wanted to nurse.  My point is that I wouldn't give up yet unless you truely want to. 

Just another thought:  I seem to recall that you were on here with questions about a URI/sinus infection.  If my memory is poor, please forgive me and ignore this.  Did you take any decongestants such as sudafed.  Such medications dry up more than just nasal secretions and may be why you have decreased milk production.  I only mention it in case you are still taking such medications. 

Haha.  That stuff is like $1 million/container.  I love it, too, though!

I love that Coconut Milk beverage by So Delicious!  It's...so delicious.  ;)

The unsweetened is only 50 calories (I love it for coffee creamer), but all the calories come from fat.  It's 5 grams of fat per serving, and all 5 grams are saturated.  I know coconut fat is different/healthier than animal-based saturated fat, but I'm just passing that on.  Each 8 oz. serving has only 1 gram of protein.

oh, thats the same amount of protein as rice milk then, the fat content is probably good for little babies and toddlers though.  I haven't tried it yet, but I LOOOVVEE So Delicious coconut milk yogurt-vanilla flavor, even though its like $1 million/ container, its good!!!

don't hate me but my cheapo HFS sells cases of 12 for $2.99.
I also just bought 2 large containers of that yogurt (quarts?) for .50 each!
i need to eat it up because its about to expire!