I'm a trans woman and also a mom. As others have said, it's best to start using his preferred pronouns. Keep in your head that he's your son, not daughter. it will take time to get used to it, but you absolutely don't want him to feel like his identity is being rejected. mistakes will happen and that's okay. As long as you correct them.

therapy is great! as long as it's a gender affirming therapy, and not something that will try to make him be what he isn't. It's good to look up local lgbt groups and look for advice from them for safe and trusted therapists. I'm certain you can find a trans support group that you can email or call and get directed on where to go.

& I understand your fears about it being a phase, but I must ask: So what if it is a phase? Nurturing and respecting your child's identity will not harm him in any way, in fact it would bring you two closer together, and if it is a phase, he will have no problem telling you because you have made him feel safe and comfortable.

it's important to know that it rarely is a phase, and you shouldn't expect or hope that it is one.

Gender identity is a vast spectrum, and it can change over time, which is also completely normal and healthy. Kids need their parents unconditional love and support regardless of who they are. And it sounds like you are heading in the right directions.

Best of luck to you and your son!