The first time a picture comes out just right, it is exciting. The second time, the face is slightly different, and the spell breaks. Keeping one face across many pictures is mostly about habits, not luck.
Write the face down once
Hair colour and length, eye colour, age range, face shape, any freckles or marks. Put it in a short paragraph and keep it somewhere safe. That paragraph is your character, and it should not change between pictures.
Change one thing at a time
If you change the outfit, the room and the pose all at once, the face often drifts too. Move one thing per picture. When the face holds, you can change the next thing.
Keep the same words in the same order
Small wording changes can make a bigger difference than you expect. Copy your character paragraph exactly each time and add the new detail after it, rather than rewriting it from memory.
Pick your best picture as the reference
When one picture captures the character perfectly, treat it as the standard. Compare every new picture against it before you post, and only keep the ones that match.
Expect a few misses
Even with good habits, some pictures will wander. That is normal. Make a few, keep the ones that look like your character, and let the rest go.