J.C.
Children often go through times of eating constantly and eating rarely. They listen to their bodies and aren't driven by cravings (like us, unfortunately) so they eat more when they are growing and less when the body is taking a little break. Don't force it, if she's still on formula she's getting all the nutrition she needs.
Also, you may want to consider a slow transition from a bottle to a cup. We often traumatize our children unnecessarily in order to force these "milestones". All it does is make life miserable for a time for our children and us.
As far as snacks go, there is this really cool little device (not sure what its called), I've found it at Walmart and Target. It has a little net attached to a plastic ring. You can put strawberries or other fresh fruit in the net part, and your child "chews" through the net and gets the strawberry without being allowed to get big pieces. It works great for little ones with no teeth.
Hope this helps.