Keep in mind that people with healthy parents have that reliance naturally, and young adults turn to their parents a lot in many cases, some for their entire lives.

So I think what is really not normal here (and I'm sad for you about this, it's true for me too) is that you don't have parents to rely on, so I see nothing wrong with turning to a good therapist to be a mentor and help you with tough things.

I think "over-reliant" is rare and would happen if you could not hold down a job, not do school, not have any other relationships, not take care of yourself (feeding, bathing, medical care, etc.) all because you refused to be at all independent from your therapist, or you couldn't make any decisions without them. It sounds like you've done school and traveled, which is great, so I don't see that over-reliance one bit. Like you mentioned, I think it's more your fear of overreliance than it really happening, and that might be because your parents aren't reliable like they should be.