Billie, I don't know that HRT affects them, but you've got great brows to work with. When you're ready to femme them up, I'd suggest thinning from the bottom up a bit and increasing towards the arch. Then widen the space between them a tad. And you'll be beautiful!

And just so you know, I thought mine were hopeless. I was expecting to need a brow lift just to get decent height, but I was amazed at how much of a difference a few millimeters could make.