I have been in unrequited love with a woman much older than me since I was 15. I am now 21. The woman was my high school teacher and I started to think of her all the time wanted to be with her & did almost anything for her attention. When I finished school the love persisted and I became obsessed. Always wanting to see her & talk to her. But because there is such a significant age difference her being in her 40s and myself being so young I'm confused if it's love or am I just lacking something from my home life. I am female also. Any advice would help?

Unrequited love, especially when there never was any reciprocation at all or hope of it, is a strange animal. A 15 year old isn't in love with a teacher more than twice her age, she has a crush. That is now an obsession, as you said. It might be a nice neat way to avoid close relationships, since it's impossible.
Sure, it may have something to do with love lacking in your young life. Care to tell us what you think that might be?

It is good that you can recognize the difference between a crush and an obsession that has resulted from the crush, that has gone on 7 years now.

The problem is, that it may be stopping you from developing normal, everyday friendships, because your thoughts are either with her, or you will be comparing others to her.

It is not healthy for anybody of any age to hang onto romantic feelings for another person, when clearly there is no relationship.

I couldn't take a stab at how and/or why this has developed, and has reached a point where your obsession may start to cause some serious trouble. Please seek the help of a counsellor (there are many who help young teens who struggle with their sexuality for instance- not saying you are, just a shot in the dark here.)

My guess is, there is more to unravel, cope, and deal with, and personally speaking to someone (parent, relative, friend, counsellor, family doctor, etc.), will help you.