taking a the crotch section in isn't just as easy as it sounds.
I had the same problem and it drove me mad.
My mom's a proffesional at sewing etc.
we tried anything... nothing worked, it only got narrower and more tighter, the sleeve ends at my feet went up, but the cloth at the crotch didn't go up...
now I tried something myself... just came to me. It's not a very conventional way to do it, so anyone who's a pro at sewing will say NO!! that's not the way to do it... no maybe not, but nothing else works for this problem...
fold your jumpsuit inside out.
then cut against the seam that's allready there up to a comfy hight, do it in steps if you need... (mark with pins when wearing to where you want it to go)
this isn't very conventional because once it's done... it's done...
then sew the thing together A few times to make it stronger with a double stitching setting on your machine., now you have actually made the crotch higher.
downside... tends to fold up on the inside of your legs, but I don;t really care about that...
here's the line at witch to cut...
I hope that helps, otherwise PM me for more help on what I did...