Unless you have a very exuberant retriever, most dogs don't understand fetch. Most dogs need to be taught fetch. In fact, a lot of dogs have to be taught how to play. It sounds like your girl doesn't particularly enjoy having things in her mouth. You can teach her to enjoy putting things and holding things in her mouth by using something like the Tug=N-Treat:

You can easily sew something like this up OR you can do it the super cheap way and use an old sock Just put some smelly liver or meat inside it and let your dog mouth it. Reward her with the food and then let her mouth the toy again. etc. etc. Over time, you can get her to hold other objects (like tennis balls or a rubber bumper) in her mouth and reward for that.

As for submissive peeing, you don't have to be super dominant to have an obedient dog. So approach her from the side and on her level. Pet her on the side and not on the head/neck. Let her "win" a couple tug of wars. Pet her gratuitously. Take some classes with her. Teach her tricks. Anything positive that you do with her will build up her confidence. She just needs to bond with you and know what you will be her calm, confident, loving leader. Also, if you know there are certain times that she will submissive urinate (i.e. when you come home from work), use that opportunity to teach her an alternative behavior. For example, when you walk into the room and she's running up to you about to submissive urinate, turn your back or leave the room BEFORE she gets to you. Wait a moment. Come back into the room. If she's still super excited and looks like she's about to pee, walk back out. Only come in and greet her when she's calmer and able to perform an alternative behavior like "Sit" or "Down" or even "Spin Around". You want to reward these behaviors, not the peeing.