Help sexing C. aneus albino

[Lygen]

hi,
i have this corydoras for 7 months or so, 2 died like 2 months ago, with apparently no reason(one had a pink/red mark on her belly)... and one other "magically" disappeared.
So now i can count 5(initially there was 8 ).
i got them all together in a small cube with 2cm water to make sexing easier, and when i look from above(like the "rules" say..) i find no differences between them, so i think they are all the same gender (females?)
so now i am here, hoping that u can help me out...

here are the pics i got from above:

and this one o got from the side:

all the 5 have this round thing on their belly, some have bigger some have smaller, i dont know if i have to be concerned about this "ball" but i dont think its normal...

thank you

[Richard B]

The one from the side (pic 3)looks female

The 'above' pics really need a light base & a bit more of a close up to give sex opinions but i'll have a go...

Pic 1 - top right and bottom left male - others female? (don't know about the one under the other)

Pic 2 - from left to right - male female male, and the 2 on the right hand side are female above and unknown below

Of course i may be totally wrong