preggo and exhausted

I'm due in June with #2 and I'm just tired all the time! I feel like I'm barely surviving. I stay at home as well as working shift work weekends and nights, 16 month old stays with dad while I'm at work. I still am home all week while dad is working, even though I work 4 days a week, so I need to do housework too as hubby works long hard days and is full time too. I feel guilty for not having the energy and motivation to do more with toddler, I worry he will fall behind because of me (which is silly I know) but I always hear how the first two years of life are the most important... And I feel so guilty for not being there for him due to this unplanned pregnancy.. Makes me feel down cos I'm finally getting my girl in wanted and I'm not even really excited.. I'm just tired and drained. Anyone else in the same situation?