Wow - invite me over! No one is going to able to define normal for you; you have to figure out what you are both comfortable with. At least you are doing it together and you need to set rigid guidelines that things stay that way - no sneaking off for private sessions for either of you. It goes without saying that you also need to limit yourselves to things that you BOTH enjoy. If either partner has the attitude 'I don't like that but I let he/she do it because they like it' you are going to get some resentment building up.

Setting an agreed limit somewhere will make you both happier.