Roses with a single active branch?

I have 2 roses that I bought earlier in the summer (late spring?). One is a Blue Bubble and one is a Black Magic. They had a rough start and battled sawfly larvas about a month ago, but both have bloomed once already and are already budding for round 2.

But, the problem is that each rose is growing and blooming from just a single branch/cane. I was told early on to cut back dying/dead canes to about an inch close to the grafting bulge - did I do this wrong? Each rose has 2-3 dried up branch-ettes where I cut them back.

I live in zone 6 and I'm worried that my single branchers don't have the foliage to absorb and store enough energy to survive the winter...

At the moment I have them in very large pots (so I knew they would survive & bloom the right colors before I planted them permanently) and had hopped to plant them in ground by now. When is it too late to plant in ground and what can I do to protect them if I have to leave them in the pots throughout the winter? (I have some experience with leaving potted flowers outside and uncovered, but those had grown normally and had been able to store their energies)

Again, both branches have just a single active branch/cane each.