18, and covered under a guardians health care plan... how do I look up what it covers without her help?

I'd prefer not to say what my situation is but I really need to get into therapy and I'm desperate for some help very soon. I've found someone who said they'd help me get there, (I'm still trying to get my license, and I literally don't have one single adult over 21 in my life, except ONE person who can take me out to practice driving, and shes afraid to get in the car with me and hardly ever has time. I have no one else to turn to. None of my friends parents even drive or would do it.) but I need to find out about my insurance. I'm covered under my legal guardian's health insurance, provided by her job. Now that Im 18, im still covered under that.. I just need to find out what it covers, or benefits or something. See, I hardly know what I'm talking about when i say insurance. I probably don't even know what to look for. My problem is I don't want to let on that I'm going, at least, not until ive already seen the therapist once or twice. I don't want to ask my guardian for hel in finding the information. I'm hoping that theres some way for me to find it out without her, because im covered under her insurance. Im scared to death that Im going to find the place where to get my answer, and someones going to ask me to produce my GUARDIANS social secutiry number or SOMETHING i can't produce without asking her for it. my psychiatrist (not the type of therapist I need to see) supports me in what Im doing and is going to help me talk to my guardian about this once I've begun to see the therapist. I'm really anxious and I wanna find out if my ensurance will cover going to see this therapist as soon as possible, and how much it will cover and if ill have a co-pay and all that. I want to find out as soon as possible so i can start going to her. The person who said shed drive me to them said she'd help me figure all this out but I want to save her the trouble, and frankly, shes taking a long time to get back to me. Maybe i can do it without her.