Hi Bea
I know what you mean about it being difficult to talk with your family about it, but it sounds like you really want to talk with them which suggests you think they might be supportive, which is a good sign! Have you ever talked with them about other stuff that you found personal/embarrassing? OCD is quite a unique experience (that's what I've always thought anyway) and probably quite hard to relate to for someone who hasn't ever experienced it, but perhaps you could focus on how you're feeling when you need to do compulsions, during and after etc, rather than going into detail of what exactly it is your doing, as your family might better relate to the feelings and then be able to understand a bit better

. I know this might not work for everyone, but I've found it easier to explain how I'm feeling as that was always the underlying reason for my compulsions. I always felt it explained what I was going through a lot better than details of what the compulsions were (although I always found them, themselves, pretty annoying!!!)
Let us know how it goes, if you do decide to talk with them