Roses in pots need regular feeding with a liquid feed (every two weeks) or an appropriate dose of granular slow-release food (not organic).
Whatever is more practical for you.
Some info here regarding growing roses in pots.https://www.gardenersworld.com/how-to/grow-plants/guide-to-growing-roses-in-pots/ You can buy food described as formulated for roses, but l use tomato food
Hello, corby008. Is it getting more than 6 hours of sun in that location? It does seem to be putting on a lot of foliage, which is good... sort of... just make sure the fertilizer is not very high in nitrogen.
Austin roses have more lush foliage than other cultivars, I really don't see the foliage on yours to be excessive. Good luck with, hope it makes a full recovery.