The more upright you are the more weight on your butt. Those skinny saddles take a little getting use to. And that might put you feeling a little tender when you sit for several weeks as your body gets use to it. If it feels like pain down in your bones of your pelvis, then that's the getting use to part. If it's muscle pain or sores on your skin, then that's something else.
What helps on road bikes it when you ride them at a fair effort or better the dynamic forces of you pedaling will reduce the weight of your butt in the saddle. But that doesn't work as well if you are sitting bolt upright. Getting a wider cushy saddle might seem the thing to do, but only if your rides are short and less than say 45 minutes to an hour. The width and cushioning will rub your skin raw where your legs are moving on the saddle.
People think I'm joking, but if you want a more normal and upright sitting position, get a cruiser bicycle with the BB well forward of the saddle and a somewhat high stack. Then you can get a wide cushy saddle. Though cruisers are strictly for leisurely riding. Their geometry is wasteful of more energetic riding and long distance riding where you want to arrive the same day you left. Or get a recumbent bike or trike.
Yes there is a lot of opinion in the stuff I just wrote. However it works for me.