need some advice

British
Ok mommies yesterday I went to the doctor and my excited immediately turned into a nightmare. I'm 21 weeks 6 days but my baby is measuring a week late is that normal? I also found out that I might have placenta acreta because of the emergency c section I had to have with my first. Of course my family is trying to be supportive and so is my husband but I would like have to have more kids I'm 25 even though I'm blessed to have the two I have but this is s hard pill to swollow I need some mothers opinion whose been through this or no anybody that has! 
P.S. I was also completely wrong about the gender so much for wivestales n difference in pregnancy cuz I'm havin another princess