length of retaining sperm?

Assuming all goes well with quarentine this year and we get breeding, my question is for next season. I know that females retain the males sperm but for how long. This year I'm breeding bell to a blizzard, but next year want to breed her to a hypo tang. Would she be good next spring to breed to the hypo? I've had females before lay non fertile eggs as they were with no males, so would I just watch for unfertile eggs next year or will she stop laying at the end of the season? Oh, our girls will only be visiting the guys for breeding.

You should have no problem breeding her with a different male next season. It is my experience that females usually only lay up to 3-4 clutches from a single pairing.