The wag is often called "sway". There a number of contributing causes. Some are external and some are from your rig configuration.
Tongue weight is the major cause of sway. Tongue weight must be at least 10% of TT actual weight. 15% is more stable. Published tongue weights are usually fictitious. They are often simply calculated from TT dry weight.
There are various methods for measuring tongue weight. You can buy a tongue weight gauge on Amazon or from etrailer.com for about $130. It will be easily portable and simple to use.
You can use the bathroom scale method. This method is cumbersome and a little complected. There are u tube videos and other sources for instructions.
You can take your fully loaded rig to a commercial CAT scale and get axle weights for tow vehicle and TT. Reweigh tow vehicle alone. The difference in tow vehicle weight with and without the TT is the tongue weight.
Tongue weight must be at least 10% of TT weight.
Other factors that have some effect on sway are tires and tire pressure on both TT and TV. Raising tire pressure usually stiffens the ride and helps to stabilize. Check sidewall labeling for maximum cold pressures. Heavy duty tires on both units usually help.
Tow vehicle suspension also affects sway. A TT too heavy for the tow vehicle affects sway. Longer TT's sway more due to wind and pressure waves from passing large trucks. Miss-alignment of TT dual axles can cause sway.
Weight distribution hitches are usually required for towing travel trailers. Some have sway limiting devices built in. Some have attachments that can be added to limit sway.
All in all, tongue weight is the elephant in the room. Tire pressure adjustment is easy to do. I recommend you do these things first.
I wish you good luck and happy trails ahead!