I have the same machine in the same cabinet! I also have a White rotary. The feet/attachments, etc. are NOT interchangeable! The needle holes in the feet etc. don't line up (about 1/8" different).
A lot of people (including myself...til I tried 'em!) think that top (some people call them bottom) clamping feet are pretty much all alike. The feet from my Reversew & the MW are interchangeable. And White & Kenmore (& I THINK Domestic) will interchange with each other. But the feet from my MW & my White don't.
The part # in the manual for the bobbins is R221. I measured one & it's 13/16th across X 5/16th thick.