With your hair being as healthy and gorgeous as it is, I wouldn't use a permanent color. Maybe try some Henna first....it's natural and won't lighten your hair, just add some rich red tones. And if you do that, it won't be such a huge change that work would even have a problem with.
Now I can't give you lots of info because unfortunately, we barely skimmed the surface of henna in beauty school before they moved us on to the typical chemical hair coloring products that I've used for the last 24 yrs.
I remember using henna and liking it a lot.
It's subtle. Takes longer than traditional coloring if I remember correctly...
Or you could use a semi-permamnet color. Again, this will add red to your own color and cannot lighten....but your hair will not be damaged.
If you decide to go fully red....let me tell you a few things. It's beautiful when you get the color you want, but red is a difficult color to keep looking fresh, as in the same color as when it's first done. We always end up using fillers to keep the tone wanted....
Whatever you do, getting a referral to a stylist that someone you know trusts and just going in for a consultation would be a good place to start.