I would say "something else", though what that is is not clear. At least in linguistics, "native speaker" requires fluency, and you self-describe as less than fluent. However, self-descriptions are sometimes mistaken, so the answer depends on why you didn't say "fluent". It is not uncommon for fluent speakers of minority and heritage languages to self-deprecate because their vocabulary is not as good as grampa's or because your "style" is influenced by the dominant language in your society. It is a common complaint by the elders that children these days don't know the language, because they don't know the word for the string used to tie on the goat's bell – because they don't herd goats anymore. That doesn't make you non-fluent.
It is very common for fluent native speakers to not be educated in their native language, because education is in some other language. I would completely delete any concept of educational policy determining whether you are a native speaker.
If you are not a fluent speaker of the language (can effortlessly understand and be understood by speakers of that dialect without sticking out as somehow "not totally knowing the language"), but you grew up speaking the language continuously (i.e. didn't start at age 14, didn't stop at age 8), I suspect that the issue is that you were not "fully engaged" with the language, mainly meaning that you didn't use it very often. For example, you might use Tigrinya (as a random example) talking to grandma, and sometimes with your parents, but everybody else that you interact with speaks English, so you don't use the language much. Your passive abilities may be much greater than your active abilities. This is a very common situation for heritage language speakers.
There isn't a special term to refer to this, probably because it is a continuum ranging from actual fluency with culturally-determined lack of vocabulary, all the way to "hardly knows the language". A distinction is sometimes made between "native speaker" and "native-like ability", where in the latter case a person started learning the language at some later point in life (nobody knows when, let's say age 12) and then becomes indistinguishable from a from-birth speaker. An alternative would be to use a language proficiency level indicator, such as the Interagency Language Roundtable scale. The problem is that this correlates poorly with what we normally understand to be "native speaker ability", instead it combines language ability with extraneous considerations like education (monolinguals may score a 0 if they are illiterate), and is impractical since it requires actually testing which for most languages is an impossibility. It also builds in requirements for cultural knowledge, which again for fluent heritage speakers may be missing.