Hi, I'm very sorry for your loss, I hope you're doing OK.
I recenlty had a D&C so I don't have any personal advice about the pessaries. I have read a few different reports about them on another site though. I think with anything like this you need to keep in mind that people are more likely to post when they have had a bad experience, it helps to vent. Anyway, I've read that they can produce quite painful contractions although miscarriage in general might produce this anyway. I guess the biggest issue surrounds whether you might need to go on to have a D&C anyway if you don't fully miscarry.
I waited just over four weeks to miscarry, I'm not sure why I was never offered anything to induce. In the end I decided to go the surgical route as I couldn't keep on waiting, it is difficult.
You need to do what's best for you but make sure if you do try to induce that you have someone with you just in case you need to get to a hospital.
Good luck and sorry again that you are going through this.