I'd ask your DF to step in and try to say something to her nicely, like "we appreciate all of your suggestions, but we're going to make a lot of the decisions ourselves. We'll share everything with you as we go along, but we'd appreciate you letting us plan our wedding." It's his mom, he's got to make the initial contact. Then if things still don't improve, I'd say something to her. The last thing you want is to have horrible memories of planning your wedding all because of her! But do keep in mind that how you and her get along during this time period could set the precidence for the rest of your relationship...and that will be for many many years! Just ask her nicely to become more of a go to person when you need help, and then don't include her in things until the decision has been made.