Hi Tina,
Young birds can be difficult to visually sex, but there are a few things that stand pretty good tests of time, of course depending on age. One of the very first things a male will do is start vocalizing, and tapping his beak on things. Chibi who we thought for a long time was a girl ended all questions when he started beating on the cage, wood, us, and such, but he was still then only about 4 months old. The barring on the tail feathers works pretty good after the first molt, but with lutino's it's almost impossible to tell unless you can detect a very faint horizontal bar somewhere in the tail plumage. Pixie, a lutino, we "think" is a female, but are not 100% certain, even at the age of 6-7 months. There is absolutely no indications of bars, but she does not act like a male, and is very quiet. I have seen her beat on the cage once or twice, but nothing like the males do. At times, she will softly chirp some sequence of chirps, but nothing what you'd call a "song"; It's more like just noise. Ginger is definitely female, as she is keeping her bars on her tail feathers, and she is now approx 8-9 months old, but the vet told me almost without question at 4 months, she was female. Some other indications of male are of course the vocalizing. None of my girls are vocal to any degree, however Missy is the loudest of the bunch, and then only to cry out when she issues a warning. Of course she chirps a little, but no singing and such, and I'm positive she is a hen as she's laid an egg. No questions there. FWIW, the females here seem to be much more intelligent than the males, in as such as they can usually figure out simple stuff like unhooking a chain, or things of that nature, where the boys are kind of "dummies" in that respect, even Smokey, who is 7 or 8 years old. He's kind of like a camera -- with no film

Females here all want to cuddle, where the males are less apt to, and Smokey will not cuddle at all. The exception to all that is Gizmo. He's very cuddly, and really enjoys his scritches. I know there are exceptions to all the sexing rules, but this is what I've discovered. There are a couple more, like the shape of the body, and palpating the pelvic bones, but unless you can do it without the bird being completely relaxed, it's useless. All the females I have are more slim and bullet shaped than the males, and the other thing is when they perch, they will sometimes appear to have more flexibility in their rumps than the males, which is just an observation, but believe me, I DO observe things like that.
If you could post some good closeup late-date shots, maybe one of us might see something that would help.. dunno.. sure can't hurt anything.
HTH