Not enough tongue weight would be my first WAG.
If the photo in your sig is your current setup, it looks like the trailer is a bit tongue high and the trucks rear end is sagging a bit... I like to tow with the tongue just a bit lower and the truck level..
But, pics are deceiving, so it could just be the angle of the pic... ;)
Adding "sway control devices" to control an uncomfortable tow is NOT a fix.. A properly loaded, setup, engineered trailer should just not 'sway' as you go down the road.. If it does, it's not loaded, setup or engineered properly IMO..
Get some weights on your new rig setup and then you might be able to see where the issue is.
Good luck!
Mitch