Many people would attempt to preach to you telling you how wrong it is to be a lesbian, or how wrong it is to watch porn. I'm not going there.
All I'm going to say is that often people get obsessed with "new things". I don't know how new this is to you, but at 16, you can't be an expert yet. Anyway, my response to you is this:
What you're doing is normal only if you do it for a while. If it becomes over time an obsession to you, prevents you from participating in the world, its not normal. But, anything overdone is not normal. Its not normal to eat too much, use too much drugs, drink too much booze, spend too much, smoke too much,... I could to on and on...
Who you are and what you do is your business, but when you let your actions become harmful to your growth and your health, then it is not normal.