I was exactly in your situation last year. I agree that Early Intervention is a great program, but unless your child is delayed in other areas (gross motor, find motor, etc.)she probably won't qualify yet.
There were a couple of things that really helped us. While I am not a fan of having babies watch much television, there were two types of DVD's that really made a difference. First, to help our son babble more we got a DVD called Baby Babble. It's very simple, but he was really interested in it. Also, it gives tips at the end for what you can do during play time to encourage her to babble/talk. We saw a difference after about a month.
The second DVD that helped us was a series called Baby Bumblebee. Each video has about 20-25 words and is great in getting the child to start saying objects (ball, pig, etc) by showing multiple examples of the word.
Our son didn't start babbling until 11 months and is now 20 months and has about 70 words! Also, he was ahead of the curve in other areas, and had started walking early as well.
If you didn't already mention it to your doctor, let him/her know that your daughter has been getting and then losing the sounds (I don't know if that's significant.) If the doctor is pretty convinced that she's just delayed, (like my son was) then maybe one or both of these videos might help.
Good luck!