I think we don't need to wait for a Sex scenes in Citrus+ because Mei and Yuzu will probably have they first time at the Wedding night and this would be after citrus+ (now I destroy all hopes sry) ;D
Nah, again, we saw their first night, in the Volume 10 Special and they almost Consecrated (or Consummate; whatever word you prefer) their Marriage but, then, Mei thought it was more important to keep writing in her journal, so it didn't end up happening
Except Mei quickly finished, and presumably they went back to what they were doing, just because you don't see sex doesn't mean it didn't happen.
Meh, I still doubt they did anything, just considering how Sabu's written em, thus far, being Useless Lesbians and everything. I'm the first one who would love to be proven wrong by seeing Yuzu and Mei finally embrace each other like they were always meant to but I've been deceived by the same old tricks, for so long, that I've given up all hope.
However, here's hoping Sabu doesn't disappoint with Matsuri and Harumin not beating around the bush and going all out