...although it took me a second to lock it in the correct book time line order. Miri was still pregnant in Necessity? So this is before the last Theo book but after the second? (Sorry names slip my mind so instead of getting it wrong...numbers are your friends.)

Necessity's Child actually takes place concurrently with some of the action in Ghost Ship (the third "Theo" book). We've been telling people it takes place "in a pocket" of Ghost Ship.