still too akward around girls 17M

Hi I'm 17M and almost finished high school, I'm 5'3 and super short. Not particularly fit or anything, no girls have ever found me attractive like ever. When I go out usually with my family, I get way too nervous around girls working in stores and I can't even test fit my shoes comfortably cuz the saleswoman was super pretty and nice, I just feel like every single gesture that I do girls will see me as a boring ass person and just weird overall. Any advice not to get too nervous around girls?