Can't squirt

My boyfriend wants me to squirt and I'm trying and I can't ever seem to be able to. He always makes sure to get me wet enough that I'm ready physically to squirt but I'm having issues because I can't and feel as if I am physically unable to. Please give me some pointers and tips or help on why I can't seem to squirt. I tried to force it out last time and I felt like I was going to but it just wouldn't go...