As I see it, the important question, from a Christian or more generally religious point of view, is not whether you acknowledge that you cannot prove God to be “really real.” The important thing is whether or not you conduct your life as if God exists.
If you do the latter, then you are not really an “agnostic”, as that term is normally used, but just an intellectually modest religious believer. On the other hand, if, because of your uncertainty, you conduct your life as if God does not exist (though open to changing your conduct if you discover evidence that he does), then you are an agnostic in the normal sense of the word.
So, for example, if you still attend Christian church services, and still believe that the claims taught in those services are (for the most part, anyway) true (even if you are aware that you have no rigorous evidence for any of those claims) – then I think you should call yourself a Christian, not an agnostic. A Christian with doubts, a Christian with questions, a Christian with perplexities (in other words, a Christian like most Christians, if truth be told), but still a Christian. On the other hand, if you have ceased attending Christian services and other Christian activities (Bible studies, etc.), this suggests that you have already decided that the preponderance of evidence is such as to leave you in real uncertainty about the truth of, say, the Apostle’s Creed. If the latter is the case, then you should indeed call yourself an agnostic.
If we are speaking in terms of living religious reality, and not in terms of textbook definitions regarding forms of belief and disbelief in an abstraction called God, it’s not lack of proof that makes one an agnostic; it’s lack of belief. You have to decide whether your problem is lack of proof, or lack of belief. And depending on what you decide, you should change your “handle” next to your name to either “Nigerian Agnostic” or “Nigerian Catholic with Theological Doubts.”
(Your current handle, “Nigerian Catholic Agnostic”, is not much use, unless it means merely, “Raised Catholic, but now Agnostic” or something like that. Strictly speaking, a Catholic and an Agnostic are incompatible positions.)