Is it normal for my definition of attractive change?

It is actually pretty normal for your taste to change. It could happen a lot or very little at all. it is nothing to be ashamed of really. It's just something I think everyone can have their own opinion on. Another thing is, you cannot help who you fall in love with. You might be caught completely off guard by who you end up with. What you find attractive is completely up to you. You have nothing wrong with you if your views on what is "attractive" and what isn't changes.