Please help me am I taking good care of my turtles...?

Ok so I have 2 red eared sliders and I want to know how if their boys or girls!!!! I counted the scales on the bottom of their shells and their are 25 and I want to know what that means. Also I want to know if I am taking good care of them ok so I have them in a 4 foot by 4foot kiddie pool with a filter and I feed them the regular tetra turtle food and I feed them 2-3 times a day and I leave them outside summer and spring. But I just want to know if Im taking good care of them or not i've had them for 2 years.