I'm 16 weeks with my 3rd. I'm having bad anxiety too. I know what to expect, I know what will happen, but still have bad anxiety. I think, how will i handle 3 kids, how will he fit in, I'm scared to death all over again! I have a 6 yr old and a 4yr old. Just the thought is sending me into panic attacks. I'm pretty sure it's the hormones, I always have anxiety a few days after giving birth, then it goes away.