Hmm, so I can have my "theory" that the internet is a series of tubes driven by hamsters? Or that you're actually a frog from space? Since you can't disprove a theory..... oh wait. You can disprove theories, can't you? You just can't logically prove them. Hmm.
Actually, gravity is *not* a theory. Newton's law of universal gravitation is a law. The difference is that a law is typically a direct relationship supported by empirical evidence. If you drop something, it falls. Newton worked out all the numbers. Same thing for Charles' law about gases and so on. What those *laws* don't do is say *why* or *how* the law works. A theory of gravitation includes a mechanism.
Furthermore, while it's not technically possible to *prove* any theory (by default, theories deal with unobservable entities that we can only understand by looking at their effects on the macroscopic world), it is certainly possible to disprove a theory. I have a theory that all matter is made up of continuous material, I shoot electron beams at a thin gold foil and observe (like Rutherford) a scattering that is inconsistent with that theory, and BLAM. Dead theory. Pardon my violent language, it's just that radical relativism makes me somewhat angry.
What I'm getting at is that you have an incorrect (and provably so) conceptualization of what the word "theory" means. Anyone who uses the phrase "still a theory" or "just a theory" has the same incorrect conceptualization of theory. The scientific community does itself a disservice by not educating people about how they use language better, but then again I've observed time and again that when the broader scientific community attempts to educate people, they tend to do things like cover their ears and say "lalala".
In closing, the "theory" of evolution is actually more of a set of interconnected theories that successfully aligns several hypothesized mechanisms with the empirically observed differentiation of species, geological age of the earth, and direct observations on the microscopic timescale of genetic drift. The "theory" of creation has no empirical support, and when confronted with actual disconfirmatory evidence its supporters either cover their ears and say "lalala" or they wave their hands and say "just a theory". BLAM. Dead theory.
There's nothing wrong with believing in a creation myth. I personally am a pastafarian (my heaven is waaaay better). But don't conflate irrational clinging to a belief with "proof" that that belief fits scientific models. And don't conflate the status of evolution as "theory" with "uncertainty". All the theory tag attaches is the notion that the entity it describes includes mechanistic and/or causal reasoning and appeals to logical reasoning in addition to empirical observations.
tl;dr: You're wrong, but you have a very common misconception about the scientific method. Plenty of people think that because you can never prove something true in all ways that any claim will do (since you can't prove that you're right, you can't prove that I'm wrong). This is known as "radical relativism", and is a dead end in reasoning.