I am a teen girl and I didn't know masturbating was haram. I didn't even know what I was doing was masturbating. Have I committed a sin? I only inserted my finger in my vagina.
Allah made HARAM a few things in the Quran, for example to eat blood, the dead and the pork. Islam is appeals to the Muslim good will, there is no point in asking for example when the pork was forbidden and someone will ask, is the donkey haram? is the chicken haram? is the animal that looks like pork haram? and so on. To me it seems like the asker wants to do what she/he wants, and he/she feels guilty about.
So then where is the guilt come from, as you mentioned you inserted your finger you probably felt good about it and that is very natural all human knows that. So you want me to tell you that is ok to go ahead and do it. A good practice of Islam is to use your judgment to, you cant expect to get answers for everything like how to take a shower or if you should use a for when eating. The general rule is to practice the religion in good will and sense.
My advice will be try not to do things that you feel guilty about. if you expect to hear a binary answer I don't have that for you Allah knows. For now don't worry and insha allah he will show you the way.
Allah Gafour Rahim.