6 year old acting out...

Chenise
I'm close to 7 months pregnant...and I have a 6 year old daughter. She is normally a really good kid and is very smart. She was never the kid to draw on the walls, pull flour out of the cabinet, etc.  I'll admit, she's definitely a manipulator and knows who she can get away with things with. She has been in trouble for close to 3 weeks now. Talking in class when she isn't supposed to, having to be told things more than once, not following simple instructions, drawing on the school desk and chairs, sneaking on her tablet, etc. I could go on and on. I'm just wondering if anyone else is going through anything similar with a kid that's an only child?? People keep telling me it's because of the baby. I'm not really sure, but it's driving me nuts.