Don't feel guilty; it's great getting your nominations in early! I wish I could too but I often like my time to hem and haw over which books to pick lol. Anyway, it's especially good you did this month because one of the nominations isn't eligible, which is so rare I don't think we've had it happen in years now.
Doomsday Book by Connie Willis was chosen by the old MR book club and one of the only guidelines for nominations is that they haven't been a selection of any book club here before. I might not've even noticed... if I hadn't read it that month back then. Although, I could still write an... informative post on my thoughts on that book, heh (suffice to say it wasn't my favourite but if you liked Willis' other book you might like it; her realistic description of a medieval town battling the plague was detailed and interesting). Anyway you've got your nomination back and can still add another nomination if you want.
As well, fyi
Love in the Time of Cholera isn't eligible either since the lit club chose it some years ago. And just to get it out there for everyone now, it might not be an exhaustive list of past sickness/plague selections but from a quick look
The Plague and
Year of Wonders also aren't eligible as we've chosen them for the lit club before, and neither is
A Canticle for Leibowitz as it was chosen for the general MR book club.