Here's a breakdown of how many of each thing we had. I say had because the smaller sizes have already been sent along to my younger sister. The truth about sizing is that you know it's time to size up when you see the back bulge coming out of the neck of the onesie. Also, if it is challenging to snap. For us, we cloth diaper. The drawback to cloth diapering is that they can be bulky, so we have sized up to 6 month clothing for daytime when baby is in cloth, but we can still use the 3-6 month size at night when he is wearing disposable diapers.
I took a catalog of how many of each type of item in each size range we had (in blue) so that I could say what I would recommend and then compared that with three sources (in red) that make recommendations. Some categories we had more than 10, but it made the graph look funny so if we had more than 10, like we did for onesies, I just didn't show it. One unexpected thing that I love is putting socks on my baby. His daytime uniform is a short-sleeved onesie and socks. Maybe if my baby had been born in winter, he would have needed more footie PJs and jackets/coats.
I'm trying to send these items to my sister because I started worrying about having enough clothes around Jan 14 (week 32) and I didn't have my baby shower until a month later, and I think that was too late for me to feel prepared.