Chinese pens generally use Chinese standard cartridges and converters, which have much larger holes than the international cartridge and converters, unless you are looking at one with Schmidt/ Bock nib unit.
I made this discovery too, after a couple of years accumulating cheaper Chinese pens: the "standard international" cartridge converters from Jinhao, Baoer etc often *don't* fit in European or American pens. I think @wolzeihan is right, they're generally at least a little bit wider, as are the cartridges - though standard international cartridges will still fit into the pens (except for Hero - they use a *much* larger, Parker-sized aperture).
Schmidt, Kaweco, Monteverde, Diplomat, and a number of other brands should work fine. If you buy a "standard international" converter from a reputable online company, usually they'll work as advertised. Sorry to hear you're having to wait to use your pen though!