I have replaced a smaller stealth with a larger stealth due to enlargement exercises and as a result had 2 different size retainer bands. I use the smaller band behind my glans. It works really well to avoid turtling. My next purchase will be a custom fit to work with the taper of my shaft due to a torpedo shape. I would suggest ordering a custom fit next time.
Also, bear in mind that the product is typically tight for a week or two. The material starts to give a little after that. Think new jeans.
Stealth has a good customer service and sizing expert team that can help you out if you have further sizing problems. As guys sometimes we like to do it all, but utilize every service that offer. And thank God for these forums. I have gotten great help from the other guys on here!
I hope the new size goes well for you.