Tricky situation as you're in OPT. In normal situations, a soon-to-expire visa doesn't go against you, meaning if your visa is set to expire tomorrow, you won't be denied an entry today. A buddy of mine travelled to Nepal just before his visa was set to expire in order to avoid the entire visa application process.

But since you're in OPT, I'm not sure what the rules are. Try asking this on other immigration forums like immigrationportal.com or trackitt. Good luck.