I have seen the same therapist 20 years, both are female. I feel very attached to this therapist is this normal?

Hey, I'd definitely say that this is normal, regardless of the genders by the way. I assume you'd define feeling attached to the same way as I define it: as having build a strong emotional bond. After all, when you regularely see someone for 20 years, it's hard not to get attached to them, to build this emotional bond. When you share a lot of intimate details with this person, it gets even harder. When this person has also been helping you move forward for the past 20 years, it gets nearly impossible not to get attached to them.

Therapists are people you connect on a deep level, especially after a long period of time. It is completely normal to feel attached to them because they are people just like you and me. The reason you feel attached to them is because after that long they become something like a friend to you. You feel weird because you feel like you should treat her only as a professional that is there to listen, help you and she does that to many other people so you feel it should not feel that personal. This feeling is completely okay and you are not the first one to experience it.