I have not done suppositories on an actual cycle, but since I do not know your age and your RE seems cool with both types (PIO, supps), I just thought you might as well make sure to get at least 1.5 or 2ccs in. However, you would not believe how hard it is to get that extra .5 or 1 cc injected in your butt. It really added to my soreness. I thought you would be good with 1 cc and your suppositories, so you would be sure to get enough.
But this advice is from an armchair RE, so you know, run it all by your real RE.