second pregnancy and I feel like

So this time around I'm not as nice as I was with my first. I notice that in the beginning of it all that I was kind of rude towards people. What is really getting me down is how little of patience I have for my 3 yr old daughter. I notice that she and I have been butting heads a lot I know fighting with a 3 yr old lol. really I feel bad that I yell and get mad at her but she yells at me gets mad at me too, and she isn't feeling the same way I am afterwards because she goes back to playing or what ever but me I sit and ask myself am I being to harsh and am I yelling for no reason. like I had to ask my husband if I was just being rude. What do you guys think , no harsh words , because I do that to myself already. Any one have any tips or any thing to help me calm down a bit.