Hi E.,
I have mentioned this to a few moms already. I have nursed all 4 of my children, and bottle fed as a suppliment when needed.
With my first child, now 18, I was told to use only a NUK nipple for a pacifier and nipple for any bottle.
With my 2nd, now 16, I had to request the Nuk nipple from the hospital.
My 3rd was a few years later, now 8, and the nurses in the hospital didn't know what I was talking about when I asked for the NUK nipple. Nor did they understand my request for the different nipple when my 4th was born.
It is a different nipple and has different sizes according to age. It is shaped more like your own nipple, and is more comfortable for your baby. It is hard and confusing for your little one to change from one shape to another, by using the regular straight nipple.
go here:
http://www.nuk.de/produkte/mahlzeit/bottles_beakers_and_c...
It will show you the nipples you should have for your little one to bottle feed after or during bf.
Or, at this age, you always have the choice of offering him a cuppy, with a soft straw. I found great ones at walmart, I think they are nubi?, and are pretty cheap.
I bought my little one soy milk, but got vanilla flavored by accident, and she loved it. She's almost 3 now, in October, and is drinking whole milk. In a cuppy (only for nap time, she drinks out of a big cup during the day), the same one I suggested to you, I add about a teaspoon of flavored coffee creamer, then warm it, just enough to take the chill off. She likes caramel, irish cream. I try to get different ones every so often.
Another thing you should really do is talk to your pediatrician about raising your baby as vegan. There are nutrients that your son should have that you may be missing in the diet you are pushing/choosing for him. My personal opinion is not to deprive your baby of what he needs and wait until he is old enough to make his own choice. At this age and for the next year, he should be trying EVERYTHING, not just what you want him to.
Good luck