gretazmama: My DD sounds like she's waking up from her nap, but once I get her situated I'll post my experience, then if you want you may message me privately for more info. Short story is that at 4m DD was diagnosed w/ almost the same problem as your DD.
Hmm, she got quiet...OK, here goes.
We went to a ped. opthamologist (hereafter knows as the P.O.) and he did a very thorough exam. He said she had one eye that was very near sighted and this was causing her brain to "discount" that eye and focus on the better eye which is a just a little FAR sighted. The brain ignoring the near sighted eye was what was causing the eye to wander or not track with the other. Because we caught it so early he said the best way to treat it was to have her wear glasses (yes, glasses) for a couple of months and see if that helped strengthen the eye. Giving the brain a clear (or mostly clear) image would cause it to track the eye correctly, therefore strengthening the muscles.
The other thing we had to do was go to a specialist at the hospital and have DD get a thorough exam under anesthetic. The extent that she was near-sighted was concerning to the P.O. so he wanted her to get checked for Pediatric Glaucoma. He said if she had it, it would be a mild case but he wanted to be sure. I agreed. Luckily, the specialist found the pressure in her eye to be normal, and did not see any reason for concern at this point. I have to say that the exam under general anesthetic was much more stressful for me and DH than it was for DD. She endured it all with grace and good humor, went home and slept it off like it never happened. I, on the other hand, was a nervous wreck the whole time she was in there. Now, The P.O. will monitor her to make sure her eye isn't getting worse and we will take it from there. Basically it just looks like she is very near sighted in that eye and will always need glasses.
I have to say that you have a good pediatrician. Many don't catch this type of problem, discounting the wandering eye as just delayed development. My P.O. said he rarely sees babies so quickly for this problem and ends up having to treat toddlers, which is apparently harder to do since the muscles in the eye are already much weaker. Thats when they have to wear a patch, or sometimes get surgery.
DD will be 7m old on Sunday and has been wearing the glasses for 2 1/2 months. Her eye very rarely wanders anymore, only when she is very tired or trying to focus on something really close to her face. I go 4-5 days in a row without noticing it at all. I have an appointment with the P.O. in 2 weeks to get her checked. If he is satisfied with the progress, and her eyesight has not gotten worse, we may be able to stop with the glasses until she is a little older and needing them for reading etc. Her eyesight is good enough that she can see me smiling at her from across the kitchen so she would be OK without the glasses until age 2 or so.
Here is a picture of her with the glasses. My awesome little nerd baby!