Different forms of "or" in Chinese

One of the difficulties ("nuances") about learning Chinese is that there are multiple ways to express "or". A specific one of those (還是; háishi) indicates a question or implies a questioning stance, while a different word(s) express(es) "or" as a statement (for that I normally use 或者 (huòzhě), but there are other(s)). I periodically catch myself in mid-sentence correcting the Chinese word I'm using for "or", which is at least better than unknowingly using the wrong one!

Do you usually buy two or three? (a question seeking an answer; Do you usually buy two, or do you usually buy three?)
你通常買兩個還是三個?
(Nǐ tōngcháng mǎi liǎngge háishi sānge?)

You usually buy two or three. (a statement, not a question; I know that you usually buy two or three.)
你通常買兩個或(者)三個.
(Nǐ tōngcháng mǎi liǎngge huò(zhě) sānge.)

I am told by a native Chinese speaker that it could be more natural to omit the 者; time will tell if I can get used to doing so.

I don't know if you usually buy two or three. (a questioning stance; I don't know if you usually buy two or if you usually buy three.)
我不知道你通常買兩個還是三個.
(Wǒ bù zhīdao nǐ tōngcháng mǎi liǎngge háishi sānge.)