advice?

i'm a brand-spanking-new female boxer. current stats are 147lbs, 5'2", 20-30% body fat. my stance may be orthodox, but my personality sure isn't! my biggest questions right now are: "how can i keep my guard up without thinking too hard? should i change my weight, or should i maintain my welterweight status? how can i extend my reach with such short arms?" any and all advice is greatly appreciated!!!