Congrats, you made the right decision. Do yourself a huge favor and stop watching rates between now and closing. You have made the decision so don't torture yourself if rates drop even further. It is a gamble to both lock and float, and I think you made the right call given your situation.
However.... IF you are somewhat of a gambling person and your mortgage person is giving you whatever the current market rate going is at any time, then you can ride it out for 2 weeks and see where rates go and lock it when you feel comfortable. That call is yours to make.
Just know that 5.5% is very fair right now.