I'm Karen, the Fixodent Community Manager. I'm glad you're doing well after your extractions! It sounds like you're frustrated with your lower denture though. A lower denture is much harder to hold in place than an upper because it moves every time you move your tongue. In time, the muscles of your cheeks, lips and tongue will learn how to keep your lower denture in place. In the meantime, your dentist can make adjustments - and it may take a few of them - to improve the fit of your dentures. But I don't think it will take too long for you to feel comfortable with the feel of your dentures in your mouth.
It know must be difficult not being able to eat right now. Try soft foods that don't require much chewing, such as scrambled eggs, mashed potatoes, yogurt and applesauce. You'll gradually be able to increase your diet to include a wider variety of foods.
We're here to support you, so please write back and let everyone know how you're doing.