Sex after C-Section

Just had a c-section and my little one was born about 2 weeks and a half now. Yesterday was my first night out with my girlfriends since the birth or the baby. Hubby wanted to treat me to a night out with them since I've been stuck at home watching baby and not gone anywhere. Well while I was out I had a couple too many drinks. Got home more tipsy than I thought I was and had sex with my husband for the first time. I know it a little early but it wasn't painful at all. Should I be worried? Also he ejaculated in me and I'm not sure if I should take a plan b just in case because the last thing we both want is for me to get pregnant again. Ftm here and my advice or insight would help a lot. TIA