Many {{{hugs}}}
We were exactly there with E at almost 13 months. Not sure where in the world you are, but I called the company for Nesquick and asked the ingredient composition for strawberry
a lot of sugar but nothing in the dairy, soy, egg or nut family is in it. Not the greatest way, but it worked. I loaded it up and made it pretty pink. Then I warmed the bottle quite warm and stripped myself down to a tank top, and E to her diaper for lots of nice cuddles. At first I had to use some soy in it too if I remember correctly, but I think what really helped was having it really sweet and really warm.
Not the most nutritionally sound way, but I had called Neocate for some trial flavour packets and it was going to be a week before I could get them. By the time I got them, she was doing well on the Nutramigen with the strawberry Nesquick. I weaned that stuff out quickly and highly recommend weaning any flavour out quick. Now she drinks the stuff cold and loves it. The other thing I did was picked up a protein shaker that 'muscle men' use for the gym. Mine has a ball in it that helps mix the Nutramigen up really well. I find it doesn't mix well at all, especially with warm water.
I hope this helps. Many {{{hugs}}} for your struggles and props for bf'ing so long. Well done!
