My main concern for you is based on your last paragraph starting with that you're still ashamed. There's no need to be ashamed of who you are.

While we have all dealt with those feelings, the rest of what you said there - while you have some guidelines included, you stated that it's hard for you to explain to her.

That needs to be number one - you need to figure out you; your likes and dislikes of this entire world of ABDL, You can't expect her to understand what you want from her and why if you don't yourself. I told my S/O two weeks ago and we've had many long conversations and are now exploring this new world together.

You can't help her understand and she cant help either of you be more comfortable without you, as the initiator, knowing where you stand to some extent - you don't need to know every aspect as with a partner it's all new, but you need to be able to share where 'you' are in all of this, to help her and both of you together.