Thank you for writing. I’m sure this is very confusing and upsetting. You are upset that you have this obsession and you are upset with the possibility of losing it. Your anxiety has taken a new form where you can’t “win”.
I can’t make a diagnosis on the basis of a short letter, of course. But I can suggest that it is possible that you are suffering from a version of erotomania. Erotomania is a delusional disorder where a person (usually a woman) starts to strongly believe that someone who is unobtainable (like the celebrity of your fantasies) is secretly in love with them. Erotomania is broken down into two forms: Primary and Secondary. Primary erotomania is called de Clerambault’s Syndrome which has the uncomplimentary common term of “Old Maid’s Insanity”. It usually has a sudden onset and there isn’t another accompanying mental illness. Secondary erotomania is found as a part of another mental illness like paranoid schizophrenia. Since you say that you have no signs of psychosis, it is more likely that you are suffering from the primary type.
It’s possible that part of the cause in your case is your difficult relationship with your parents. More likely, it has to do with loneliness and not being successful at finding a partner when most teens your age are developmentally and appropriately exploring their sexuality and relationships for the first time. You long for love but haven’t been able to figure out how to find it or who to find it with. Some studies also suggest a genetic propensity for the disorder but that isn’t yet clear.
I think you would benefit from treatment. You said you have anxiety and depression but you didn’t mention if that diagnosis came from a professional or only from your own reading. I suspect that you haven’t engaged in treatment for either problem since you didn’t mention it. The emergence of this obsession suggests that your anxiety has become more serious than you can manage on your own.
Please do yourself the big favor of getting help from a licensed mental health counselor. Erotomania has a way of becoming chronic if untreated. Individual psychotherapy has been found to be effective. Sometimes some family therapy is recommended as well.
I wish you well.