Uhh... wow. You can definitely pick your own spot with a range like that! If it's comfortable, it's unlikely to be damaging anything, and your teachers may just believe that chest voice is always evil.

As for me, my high soprano range disappeared at around age 13, and I was left with my "easy" range being exactly the same as the untrained alto listed on that page of ranges. When singing in choir, anything above F#5 was difficult, and a G5 or A5 was a strain that I could only do sometimes. I can't even scream high.

A friend who was definitely a lyric or coloratura soprano could not sing anything lower than middle C, and even that was a strain for her. I've sung as low as the D or C below middle C, but that was usually also a strain and I stopped. F3 is fairly easy though.

My voice isn't heavy enough for contralto (athough it can be loud enough sometimes!) and I kept getting asked to sing mezzo, which would place too much of a demand on my higher voice, especially in quieter parts of songs. Then I would be unable to sing high for a while after rehearsal. A soprano told me that the top of her range is something she really cannot sing quietly... so it would appear that D5-G5 really is the top of my range, because I really can't sing it at less than mezzoforte at the softest. It just disappears.

I don't know why the choir directors objected to my "chest voice" since it wasn't even as heavy as that of a true contralto, and I was asked to round out the tenors a few times when they had parts too high for them.