Be patient with yourselves (him and you). In just 13 days, you are still just getting to know one another. When my oldest son was only four weeks old, I also traveled alone with him by plane from Denver to Chicago. I was a nurse-on-demand mom, too. The plane trip was actually a breeze. He had me to hold him the whole time. When he wanted to nurse, I nursed, so he was happy. Make sure you nurse when taking off and DEFINITELY when landing. This will prevent his ears from popping. When he was only 13 days old, I was very apprehensive. It all turned out fine.
PS A couple of ladies recommended fans for the back seat. Excellent ideas. I purchased last week, a clip on fan that plugs into the lighter for under $9 from WalMart. I also purchased a battery operated one from WalMart for about $12. Both work well.
Traveling in the car with him was challenging for years! Some tips I will share include:
letting him nap in his car seat from time to time while you are at home. This helps him get used to it. He's used to being in the womb. Everything else seems strange and lonely.
I always had a baby bottle with water handy while driving so I could pacify him until we got home or to our destination. Sucking really calms babies.
I assume you will travel to Orlando with your husband. Whoever is not driving will have to be responsible for comforting and entertaining your son. (That's the bad news. It does take extra energy.) Sometimes, just holding his hand or having your hand on his tummy will keep him calm. Sometimes smiling and cooing will be necessary. Plan to make frequent stops so he can be out of the carseat to stretch and nurse. Keep him swaddled tightly and he should feel more comfortable in new surroundings.
I remember these challenging times as though it were yesterday. My oldest son is a freshman in college, turning 19 next Wednesday. He was my most challenging. When all is said and done, I'm glad I had him first. He broke me in well, and his brother (17) and sister (15 1/2) have been a piece of cake. (And we now live just north of Orlando.)
I wish you all the best! Take a step back and try to enjoy your travels with him. It's just one of many new experiences you will share. When you reach your destination(s), your friends and family will be delighted to meet your son and help you celebrate this new chapter in your life!