If you have your bm's with just the creme brulee, it will look insipid with black & white. Those basic colours need to be lifted with the gold, orange and red as well. I can't imagine a prettier colour combination. Red & white (or cream) are very popular colours, and it is so nice to see something different, especially in Autumn when those colours are so beautiful in nature. You are reflecting that.
I'm a big fan of flowers but I prefer the one colour in the bouquet rather than mixed. My opinion is to give the bridesmaids, groomsmen impact, you and the groom either creme brulee or adrenalin and then page boy gold coast (and maybe the parents too)
But ultimately it's up to you, you have to be happy with it, not your step mum or anybody else. I think you've chosen beautiful colours so I'm sure whatever you end up doing will look great!
I also wouldn't stress too much over matching the reception flowers. As long as you have a general colour scheme/the colours don't clash totally with your reception flowers then it's fine.