Like you I went with the 28 day seasons. I also turned aging off in my played households and I went so far as to lengthen pregnancies to last about as long as irl pregnancies would. And I also waited to age kids up until the same day of the following sim year. So my sims are pregnant for 3 seasons. Whatever day the baby was born gets noted and it won't age up until the corresponding day the next year. Same with toddlers, children, teens and YA. Once they hit YA though I slow it down to give them more "years".
So, Im pretty proud that I waited to age sims up like I said I would. It was really hard not to age the babies up right away lol.