Please Help -- Is skipping 2 weeks 2 shots, or 1 shot?

I read that skipping two weeks means you should start at 2.5mg, but is that skipping two weekly shots (over three weeks?) OR skipping ONE shot (over two weeks)? Basically, my last shot was Wednesday Sept 17, and I missed one shot on Sept. 24, and now it's Thurs Oct 2, so the 15th day since my last shot. I was at dose 5.75mg. Should I do 2.5mg or is it okay for me to do 3 or 4mg?

Thank you.