If you feel like you're fumbling your way through it, that pretty much requires that you level-grind your way to comfort. :/
If you feel like you have to oversimplify things, however, that has a faster fix. You can identify topics that you use often or want to use, and beef up your vocabulary for them so you don't have to reduce your ideas to your current vocabulary. This is where people get things like "Business Spanish" classes to build their performance in a bilingual workplace.
Or you can pick a more rarefied topic and learn some vocabulary words for it. There are plenty of museums with Hispanic art, for instance. Why not look up Spanish words for a wider range of colors, shapes, symbolism, names of painters, art concepts, and so forth? Then go out to a museum and talk about those things in Spanish. Often you can find places that have a self-tour with a Spanish track, which is another way to practice.
Spanish art vocabulary:
Here is an awesome video lesson in Spanish art vocabulary. I was surprised and delighted that I could understand almost all of it, despite never having studied it. :D (Yes, I just blew 20 minutes on Spanish art because it sounded fun.) The Spanish comes first, then you get the translation a few seconds later, so see how much you can figure out. It's a little slice of Terramagne. This kind of stuff is all over T-America, encouraging people to use their spare languages. Museums will pitch art language for whatever cultures they have art from. Zoos often choose Greek or Latin (because of the scientific names) or languages relating to the animals' country of origin.
It's not oversimplifying if you can learn to talk about sophisticated topics. Pick something that sounds cool to you and try it out. If you explore one new topic a month, at the end of a year you'll be conversant in a dozen interesting themes. \o/