Bolding is mine....
Well you certainly don't want to travel w/ me then. Because on our last trip our family of 4 checked 7 bags on the way down and carried on 4 bags plus our 'larger than usual' personal item.

I 'forgot to nest a packed suitcase inside of an empty one. So we had to go to Target to buy an extra large duffel bag for the way home. so on the way home we checked 8 bags, plus our 4 carry on's, plus all of our extra 'personal items', some of the carry on did contain med equipment though. And I use pretty much everything I pack. Last year, though, we had one of the smaller suitcases that was just our costumes for
MNSSHP.
Back on topic...
And don't forget to add the $6 per ticket seat selection fee if you wish to utilize that feature. I personally, using BWI (but have used Dulles) would definitely wait. I think you will find much better fares w/ SW. but do what your head tells you to do. Have a great trip.