Ill give you some extra tips. What you should do is
Put barrels, logs, stumps, big rocks etc, in your jumps to make em higher and so you dont have to use as much dirt. Do the some for your landings. Also if you want a jump that would kick you a bit higher than usual put a log at the end tip of it nd put a bit more dirt on top of it then pack it down.
You can also cut down a tree or if you know any1 that can. Then cut the tree into logs no less than a metre. Then line them to make some whoops. Space em at about 30cm then cover then with a bit of dirt. Thats how i did my whoops and they are good as. Also with your down hill jumps dont worry about a landing just have the landing to be the hill. And for your up hill jumps dig into the hill and make a set-up jump like that you would have bigger jumps. And heaps more fun.