It really depends on the relevancy of the things you talk about with them. If you're talking about things that you feel are directly related to regression and you want them correlated during their evaluations of what you tell them then it could be relevant. You don't have to reveal it to them though. You never have to officially "come out" to someone, and a good therapist should be able to identify your personality (while likely not using terms we use like "little" or "regressor") as being a bit quirkier than others they see that are your biological age. There is nothing wrong with you though so "coming out" may be completely irrelevant to them, as sometimes even sexuality (something that people regularly need to "come out" about to close ones; again, not anything "wrong" and may not be related to the therapy) is irrelevant to the reason a person may be seeing a therapist.
Sometimes the label you choose itself makes things messier, but that's my own personal opinion, because it subconciously tells the person that something is "different" and potentially "wrong" then if you've felt the need to hide it and give it a special name. It's human nature to look for social defects and try to "correct" them for safety.
So, you may want to avoid the "Little" label since they may not be educated enough to know of it just yet (forcing them to try to quickly find reliable information--which is pretty scarce in itself
). I would also suggest to avoid using the "regressor" word since regression in the medical sense is rarely seen as positive and within psychology
specifically it is a bit of pseudoscience.
You may also consider not referring to it so much as "a lifestyle" but, rather, a personal identity or personality trait.
If you choose to make it known that you are a bit atypical in personality then I would suggest revealing statements that are more descriptive than labeled such as:
- As for who I am, I've identified myself as a person who is more childlike than other teens.
- I believe I have a personality trait that is more childlike or childish than my peers.
- I tend to lean to liking more things targeted to and for children and I'm comfortable with being a little silly and different in comparison to other people at, say, school or church. I'm kind of like a child at heart or just a big kid that never quite grew up but, well, haha, certainly did grow!
- Sometimes I just feel like a big kid who never quite grew up like everyone else, if that makes any sense to you. It can be fun but I certainly have my quirks.
- I tend to partner with and have romantic relationships with people who are more [childish or parental] than others since that seems to counterbalance my own personality.
If you want to address your regressive trait directly in hopes of them helping you to "correct" it or some such then you might phrase it like:
- Do you know how people talk about that Peter Pan Syndrome stuff? I know it's not an actual term or diagnosis you use, but how people talk about it is sort of how I see myself? I really feel like I struggle to grow up like everyone else has and sometimes I don't know how to deal with that. That's why I believe I'm here today.
When you make it seem less of a "lifestyle choice" (or even something they should consider as "abnormal") and more of an identity of who you are then there is more pressure for them to accept that as a valid part of yourself versus an area that needs to be "resolved" through therapy. Facts are not optional, and true personality traits are not necessarily areas of "correction" for therapists.
The more natural and fluid you describe your identity within the community then the more confident you appear to be about yourself (and the less they are inclined to feel you need their assistance in "correcting" that part of your life
). If you don't feel that being a little is specifically a core issue you need to deal with and "resolve" during therapy sessions then you may not want to make a big "reveal" so much as simply just lightly stating personality facts and traits throughout normal therapeutic conversation.
Also remember that if you do some sort of "reveal" to a therapist then the emphasis you're placing on "coming out" to them is going to be taken as something they should question and focus on. They aren't going to have no follow up questions as to why you feel the way you do so you have to be prepared for many questions, including possible questions about "the worst assumptions", without getting heated or irritated. They're just trying to help though and have the best of intentions to help you be the best you that you can be.