I believe your trailer is a single axle trailer with no slides. When designed and built, the objective was to have the trailer "close to the ground" and there was no need to "incorporate slide clearance" under the trailer, so it was built with the springs under the axle, giving a lower trailer floor height.
There are two ways you can achieve height. One, probably the easiest, is to install an "axle conversion kit" which will attach the springs "over the axle". By moving the axle position to under the springs, you'll gain around 4 inches of trailer floor height.
Another way to gain height is to place a "lift block kit" between the springs and the axle. That will raise it "less than flipping the axle"
Here's a link to the "axle conversion kit" that moves the axle position:
https://www.etrailer.com/Accessories...71-384-00.html and the "axle lift kit" of which there are several "lift heights":
https://www.etrailer.com/Accessories.../LC425750.html
To me, the most effective and least expensive is to "flip the axles", but it also means the most "work to achieve results"....