I can completely sympathize.
I am not what most people think of when they picture the "perfect" mom. I am the one who works outside the home while my husband works from home and gets our daughter to and from school and I like it that way. I would love to be a stay at home mom but it would drive me absolutely insane! I thrive on the chaos, but I couldn't do it all day every day. Those of you that do it have my absolute awe and admiration.
My job takes me to the back country and away from home for days at a time and I'm involved in several volunteer organizations that often take me into the back country.
That said, I miss my DD (8 years old) even when she goes to spend the night at a friend's!!! I find myself wandering around the house, not knowing what to do. I do take her with me on trips and projects as much as possible and I wonder what I will ever do when she's not here. We only have the 1, so that makes it even harder.
But, I have a couple suggestions that might help quell that empty nest syndrome.
First, if you think you are up for having another child in the house, consider taking in an exchange student. Because we always wanted more children and adoption has not been an affordable option for us, we host exchange students every other year. What an amazing experience!!! Three years ago it was an 18 year old from Brazil who still calls us mom and dad. She led to having a young man live with us who's parents were moving and wanted to finish his senior year here. He recently moved back to Kodiak and spends his holidays with us. And we currently have a 16 year old Danish girl whom we absolutely love. Sure, you ultimately have to let them go too, but then you have all these wonderful places to visit and you end up with children all over the world.
That's my next suggestion: start a travel fund now and as your children grow and spread their wings, take that opportunity to visit wherever they choose to land. My folks encouraged my brother and I to take every opportunity, which we have and which landed me back in Alaska. But, unfortunately, they didn't save enough to travel often and so we don't see them as much as we'd like.
Third, if you are really brave and big-hearted, consider foster children. Yet again, you are facing having to let them go (if you are not interested in adoption) but think what you could do for those children in the brief time they are with you. I'm a big believer in the "love conquers all" theory and I think that having someone who truly loves and cares for you and isn't afraid to show it, no matter how brief a time, can change a person's life.
Best of luck! Sounds like your daughter has an amazing, caring Mother.