Although you don't specify, it sounds like you are using standard Sterling. I was taught metalsmithing with standard Sterling decades ago, so used it for years.
However, may I suggest that you try working with Argentiuum Sterling (AS), especially the AS solders. There is much in the archives about the differences between AS and standard Sterling. In a nutshell, AS is tarnish RESISTANT, does not fire scale, is a whiter color, work-hardens more slowly (and can be hardened in a toaster oven), and solders very much like gold. On the downside, it is brittle when hot and large pieces will slump if unsupported. Price is slightly higher than standard Sterling. I get it at Rio Grande. Check their website for technical info. Stuller carries two other tarnish resistant silver alloys, each with different benefits. The website also has technical info.
I only use AS solders, even on the regular Sterling that I still have in my stock. It is a better color match and in general flows at lower temps than the other silver solders. What's not to like. It least try the AS solders to see if you have more success.
Judy in Kansas, who sees a lovely day and would like to get out and put some time into cleaning up the garden, but will stay at the bench preparing some pieces.