Jasper also has reflux, and struggles with constipation. We've avoided grains, since even homemade whole-grain oats seem to bind him up. Also no apples, and definitely not bananas, since even the ripest seem to be trouble for him. I've been giving him 50% white grape juice, about 2 oz once per day and it's REALLY helped. Having an older one, I can tell you that he won't get hooked on juice (we used it with Josie too, until she was around 1 year, then stopped...now she gets very little juice [only orange, and only with weekend breakfasts] and never missed it). We also give a lot of yogurt, which he loves and has been a help, as well as pears, yams, peas (mixed with applesauce), and mango. Oh yes, mango is very fibrous and works great.
Finally, if she's struggling with other things, you should definitely AVOID blueberries until 1 year. They're a very common allergen (same with corn & strawberries).
I used "The Super Baby Food Book" by Ruth Yaron with Josie and Jasper, and it's been very helpful on figuring out what foods to feed when.
Goood luck,
Amanda