I am so very sorry. I haven't had a miscarriage, but I did have a stillborn daughter in June at 25 weeks of pregnancy. It was a regular labor and birth. I can't answer your question pertaining to how long you will be in pain with the miscarriage since I do not have personal experience, but from what I've read on other websites, it sounds like it might be a week or so. Again, that is not based on me.
I just wanted to tell you I am sorry for your loss. I know that might not make you feel any better, or it may, either way is fine. Grief is a very unique experience, and while others can guess how you feel, or tell you they know how you feel, you are the only one who knows what its like for you.
You didn't ask for any advice, but I'll throw in my two cents anyways. Consider naming your child. I've read that it helps to acknowledge that this was a baby. You don't have to name your baby now. Its never too late.
Please know you and your child are in my thoughts and prayers. Feel free to PM if you'd like to chat more. Many, many hugs to you, mama, and I'm wishing for happy moments for you.