Hard to tell from the pic...lots of glare...but if not she soon will be if you have males around
It looks like your tank may be densely planted enough that you don't have to bother with the trap...any java moss or guppy grass in there. Who else is in the tank?
Well, the plants that you are seeing are from one of those things that you put at the back of the aquarium... Like a background... Good to know it looks good though . Mind, I do have 6 plants, a rock formation, and a few other ornamental things in the tank.
My 30 gallon tank consists of: three platties, seven harlequin tetras, 11 neon tetras, one serpae tetra, two albino cories, one peppered cory, one bronchis splendens cory (not sure of the common name for this one), five glowlight tetras, one leopard plecostomus, and one dwarf aquatic frog.
She could be look out for the gravid spot that would definitely indicate that she is pregnant. I have two female and one male platy but no pregnancies yet. I agree if you have a heavily planted tank you probably don't need the trap.