I wanted to respond so that you know you're not alone in these struggles, even though our experiences were not exactly the same.
My now-5 yo DD Sophie has Down Syndrome, and we have dealt with a number of feeding issues since her birth. She was a preemie and was O2 dependent for a while, but with a lot of effort, I did eventually get her nursing exclusively at around 3 mos. of age. Then, at 10 months, she had the misfortune of cutting her first 8 teeth simultaneously, which led first to a week-long nursing strike, and then to a severe biting problem. :( I worked for over 6 weeks to get her back nursing, but she never learned not to bite, and after repeated breast infections (from the bite wounds) and a great deal of pain/anxiety, I was finally forced to switch to exclusively pumping for her at around 11 1/2 months.
That's when most of our problems really started. She was still exclusively on breastmilk, had low oral muscle tone, and was an extremely poor bottle/cup/straw/sippy feeder. I tried absolutely everything! At our lowest point, I spent a couple of weeks having to dropper-feed her (a 13 month old!) breastmilk all.day.long. During this period, her weight flatlined and her overall development, both cognitively and physically, came to a screeching halt. It was so incredibly stressful!
We were hooked up with a feeding therapist, who eventually got her to take a Haberman feeder, and then started working with us on solids. Oh, and I forgot to mention that she had a dairy allergy, so that eliminated a lot of otherwise good nutritional sources for her. Like your DD, she had a lot of trouble moving food from the front to back of her mouth and would frequently gag or choke, which only strengthened her food aversions. Purees didn't work for her at all at that age. The only foods she would tolerate at first were crunchy things that dissolved easily in her mouth -- rice puffs, cheerios, corn puffs, that sort of thing. She steadfastly avoided all fresh fruits and vegetables (though she would suck on fruit leather and eventually would eat small chunks of cooked veggies, like sweet potatoes, carrots.) Mixed textures (chunks in a puree, for example, or dipping things in a puree) were also a no-go. Finger foods ultimately worked the best -- I just had to make sure they were very non-chokeable, since she wasn't very adept at muscle control, and that I only put a few of anything on her tray at a time, b/c she was also terrible at portion control, and would stuff everything into her mouth and promptly choke. Ah, good times. I spent the first 3 years of her life putting olive oil and coconut oil on everything and giving her countless avocados (one of the few fats she would eat.) I pumped for her until she was 18 months old, which is when I weaned her older sister (at 3 1/2 yrs.) and my milk supply subsequently plummeted.
In our case, the feeding issues haven't gone away completely (she still refuses fresh veggies, although she'll eat them cooked, and most fresh fruits, but again, will eat them in other forms, like applesauce or fruit leather), but they have greatly improved. There was no magic bullet, though, I'm sorry to say. It was gradual and mostly a factor of time, as her muscle tone improved and she outgrew her reflux. Now, at 5, she has a great appetite and her weight/height are normal (for her growth curve.)
I hope my ramblings give you some hope that there can be a light at the end of the tunnel, and most of all, comfort that you aren't alone.