Honestly fcpx is garbage, stick with iMovie. FCPX is basically a slightly "more advanced" version of iMovie, and not worth the price. Your edits will not get better. You can be just as creative in iMovie as you can in final cut.
My advice is save up a for a couple of years ad get the adobe creative cloud. It's expensive so it will take some time to save up for, but definitely worth it. Also, I wouldn't recommend upgrading necessarily you have a reason. For me personally, I upgraded to adobe creative cloud, because some of the jobs I was getting required it. The work flow is also a lot better imo, there are tabs for assembly, editing, color, and sound; it makes it very easy to edit exactly what you need. Also with adobe creative cloud, you can set up a behance account for free. Bechance is basically like instagram for professionals. It allows you to share your projects, and even get jobs through the platform