Do it hun, doesnt matter about the symetry, doesnt matter about the 3 under 3, do it because u want to. do it to love another little life
i have briefly bought up number 4 with DF, idealy i'd love to try asap and have number 4 this yr, but he has his own understandable reservations about it.
sounds to me like you've made ur mind up, and if u do it at chrissy time you'll feel better for being more financially secure and wont have that extra stress next yr