There's a small bed in the corner of my landscaping. It's separated from the landscaping coming down the side of the house by a stone drain for the downspout. Behind it is the back porch and it's edged by grass on two sides. I want something in the corner of the bed. Currently there are three English lavender along the curve of the two open sides with a red double knockout rose at the center of the curve. There's a catnip in the center of the bed and catmint filling in around it. The corner closest to the house has orange canna. I want something on the other corner that's out against the yard. I'd like it to be in the five to ten foot range with a spread of no more than three feet. A little taller would be better because I want it to provide some color above the lavender and rose as well as a little privacy for the porch. Along the back of the porch are orange rocket barberries so the plant would be a transition between the barberries and lavender. I'm not overly particular about the color but yellow or orange would stand out from all the purple or red would match the rose. A dwarf tree would be great there but I'm concerned about how close it would be to the concrete porch. My best idea right now is a to put a trellis there with a clematis, there's already a sturdy upright that I could connect it to. I would really like something with a longer bloom season though. It's full sun, zone 6b, with rocky clay soil.
I mean, if you want color, scent, and a long bloom time, you could go with a rebooming rose, like Scentimental or one of the Knock Out types. Most good rebloomers aren’t quite as tall as you were hoping for, although sometimes you can find them grown as standards.
There’s also lilacs, which even though you’d get only a short bloom, you could prune to whatever look you wanted.
If you want to just do a green dramatic accent, Ilex ‘Sky Pencil’ fits every other one of your requirements.
Probably the best tree that roughly fits what you want is Caragana arborescens ‘Pendula’. Not a rebloomer, but pretty flowers, a nice weeping habit, and a pretty yellow fall color do give it year-round interest.
I like holly the red berries look nice through snow. The weeping pea is also interesting, I haven't seen that before. It doesn't need to rebloom if there's fruit, fruit is visually interesting too.
Japanese Holly actually gets small purple-black berries (assuming a male nearby). Still good for birds though.
The peashrub can set a sort of tan fruit; but after flowering what people usually enjoy is the weeping form, pruning it to be more open to show that off (it’ll end up looking sort of like a snuffleupagus if you don’t prune). ‘Walker’ is a variety with more delicate foliage so it shows the weeping habit better.