i used to be a professional dancer too and since i had my daughter i'm more of a workout junkie. it *****, but my intuition is that it is better for you to NOT overexert yourself while pregnant. overheating, for one thing, presents a danger to your baby. also: you are NEVER to exercise to the point of fatigue.
have you tried doing prenatal yoga? i love it, and while the strengthening is very gentle, the stretching is really helpful, particularly when you have tight muscles that are now stretching out (which most dancers struggle with when they are pregnant!).
good luck!
Well because you are in your second trimester, you are probably jsut getting your energy back, if not hopefully soon... and yes its important to exercise but even a nice walk counts... do fret too much about it for now as you do seem busy and if your tired its best to listen to your body and rest... maybe you can talk to your hubby about going for a short walk around the block after work or on days off and encourage him to be your support as this clearly is bothering you... and remember, your pregnant take it easy, rest when needed and eat a healthy well balanced diet... after baby comes and your feeling better, you can get back into it... but for now do what you can do... but nothing to strenuous :)
Congrats and good luck!