Small or large Fleurcup?

Hi, I am a 28-year old virgin, and I have used a small Fleurcup before. My periods are moderately heavy. There were a few times when I was using my small Fleurcup but leaked suddenly and dramatically in the night. At those times the cup was never full. I also usually leaked a bit in the daytime, not in such large volumes and not worse than with a tampon, but I still had to be vigilant. And I wouldn't dare to wear white! Apart from that I was comfortable with it: when I first got it I cut the stem a little shorter, but otherwise it suited me. I am very active as a runner and dancer.
My cup got lost so I need to order another. I am wondering whether it would be sensible to change to a large Fleurcup - would that prevent the nighttime floods?