What should I write to her to see if she's my birth mother?

I am a 15 year old girl and decided to find a way to get in touch with my birth mother.I started doing some research and already found out some things.I know where she lived exactly when I was born,where her parents currently live,what kind of job she has now(biology teacher) and I think she is married to a priest.and I know her maiden name.and she knows who is my adoptive family and in which town I live.but I’m not sure if she lives in the same town she did when I was born.but if she still does,then it’s close to the town in which I live.I started searching for her on sites like hi5,my space,face book and found one profile that I suspect it might be hers.I’d like to add that person in my friends list and send her a message,but don’t really know what to write her,as I can’t be sure if that woman is really her.I really don’t know what to write to that woman,but I need to find out if she is my birth mother.what should I ask her?what should I write to her?should I talk to her in a direct manner or be subtle about what I want to find out from her?I really need some good ideas and tips,as I don’t want to scare that person and of course I’d like her to reply.please help me,I would really appreciate it!