This may or may not happen. My male will jump 5 feet off the bank into the river on a retrieve and go through about anything. Of course he is a 120 pound bull of a lab. My female was more timid, girlish like about entering the water. She'd walk up and gentle sway in. She'd still bring back everything but in her own way.
Keep up the gentle entry into the water. Even if you can find puddles, deeper and deeper that the two of you can walk through together. I would play with mine in the water as your doing with the dumy until one day they both just went over ther heads.
We would do water retrieves about every other day. Some days though the interest would not be there and that's OK, we just made them play days. Keep it up, my lab did his first double retrieve at about seven months.