Freaking out possibly pregnant

Ok so my daughter is almost 5 months and I’m EBF her. My period still hasn’t returned and I’ve been feeling so nauseous since yesterday. I’m so freaking out my hubby wants me to test to make sure I’m not pregnant but I’m so afraid to. We want more kids just not this soon my dr said not to get pregnant so soon as I had a c section and they need to be 18 months apart. I also have a almost 5 yr old son. Has anyone experienced getting pregnant while EBF after a c section and everything was fine! I’m freaking out!!