In my male, it wasn't until about 18 months that he decided he was obsessed with retrieving anything. As a pup, wrote him off as a dud. But kept working with him to become a hunt test dog. At 6 to 8 months he was retrieving birds from land and water but with no ounce of inner drive. And no bumpers - could not care less about bumpers - which is why I put him on birds - to build drive. simply to make us happy. Despite that, he got his JH at 14 months. At some point, and I don't know why, he became absolutely obsessed. Balls, bumpers, birds - anything. He is now two and drives us crazy with wanting to retrieve.
On the other hand - just picked up our new puppy who is 8 weeks old today and she was born with tons of drive to retrieve. When we went to pick her up, she retrieved a live pigeon three times. She goes after anything we throw and brings it back!!
So don't give up, it just depends on the dog. Your pup will likely come around if you nurture the retrieve drive and stay patient and don't ruin pup by showing frustration or applying too much pressure. My dud will be a senior hunter this fall. Delay from ear infections this spring.
Good luck and stick with it!!!