It would be helpful to know why your teacher advised against student models, which are smaller. Perhaps because they generally lack some strings that you will later need for more advanced literature.
You are tall enough to play a concert grand or semi-grand. The key is knowing where to sit, relative to the instrument.
If price is an issue, consider a used harp, but have it carefully checked out by a trained professional first. If weight is a problem, consider Camac harps, which often weigh less than some other makes of comparable size.
Contact the major harp companies–Lyon & Healy, Salvi, Venus, Camac, Aoyama–and ask for brochures with the specs on their various models so you can compare price, weight, number of strings, etc. Then you can make a more educated decision.
How does she do it?! I am 4′ 9″ tall and have just about decided that
32 strings is my maximum reach! (And that felt like a stretch!) Is
there a better way to sit, turn the harp, what? I would like to be able
to have more strings, but have been feeling like, “If I can’t reach
’em, why pay for ’em?” Is there a book or video somewhere that would
help with a good – posture and reach wise – positioning? (I also have
arthritis and a bad back). This is new ground for my mentor who has
never worked with someone as short as I am.