Toddler worse with mom

My daughter is seriously the happiest child. Super playful and outgoing. But when it's just the two of us at home she cries and whines nonstop. And it's not the same sound as when she's actually upset. It drives me nuts. My husband has noticed it now and has been giving me breaks. I'm tired. I'm pregnant and I just want to enjoy my days off work with her but it's just constant. I don't know how to help her adjust her behavior. I understand she's learning emotions but why only me??