There's no reason you couldn't have another kid if you really wanted. You could use a sperm bank, ask a male friend for help, or adopt, just like any other lesbian couple would do.
Sorry, that's the extent of my useful advice at the moment! I think it's going to be ok though, even if maybe things should slow down even more, for all involved, in light of this news.
Me, 30ish bi female, been doing solo poly for roughly 5 years. Gia, Clay, and Pike, my partners. Davis, ex/friend/"it's complicated." Eric, Gia's husband. Bee, Gia and Eric's toddler.