At a young age all Andinoacara are difficult to sex, even with the most clear photos.
You will need to post a very clear broadside to enable anyone to give an accurate gender ID.
At minimum, Something like these shots below

The one above is a male, note the dorsal fin point extends as far out as the caudal (sometimes farther with maturity).
Whereas the females dorsal extends only half way into the caudal area

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Below another shot of a male, showing that extension, but also note a lack of black melanin throughout the body

Above and below a female, slightly more melanin, the dorsal fin shorter, and notice the more prominent irrideceent blue spangling on the gill plate, and jaw area

below a male in the foreground, note the longer dorsal"and" extension of the anal fin

I will also note the males are more streamlined, a bit less boxy shaped than females, hard to see if they are not together in the same tank.
And to throw in more confusion, during fry care, the males melanin also intensifies.
The male in the photos above is about 7", female 5" (another indicator, males are generally larger) at the same age.
Trying to determine gender and 1 or 2" is impossible, because these traits are not developed or visible.

I find the best way to get a compatible pair, is to buy a group of 6 to 8, and allow the group dynamic to play out

