Hi P. - I am a mother of 17 month old twin girls. I STILL have the same problem with one of my kids. Sometime she eats great, sometimes she just refuses (actually most of the time)...but, she LOVES the bottle....still. At about 9 months, I was at my wits end with the spoon feeding and decided to pour the baby food in the bottle with milk/formula.
To this day, I still add baby food, yogurt and/or cereal to every bottle...and try to spoon feed or finger feed once per day as practice. She is still getting all the food she needs....but in a smoothie. My other child does great with the spoon and other solids. My philosophy is all I can do is keep introducing it to her and hopefully some day she will get it. I don't want to force her because I don't want her to associate eating with a negative experience.
Hope this helps. Drill bigger holes in your bottles if you decide to try this. Start slow, so they don't overeat. Now, I can add an entire jar to an 8-ounce bottle. Give extra water since the bottles are so thick. My girls have sippy cups with water they carry around all day.
My email address is ____@____.com me know if anyone else has any better ideas! :) Good luck!