Thanks for the replies folks, I might get a couple of those plastic containers to milk into and then strain into wide mouthed glass jars to keep in the fridge, at least that way the milk wouldn't be stored in plastic.
Gosh how would I know if I was damaging the udder (I'm worried now)? One of the girls' udder half is definitely getting bigger (I'm milking it twice a day), but theres not much change in my other girl and the teat on that side is all flat and floppy, getting about a tablespoon out of that one. Shrugs!