Here it is. Better then words.

It grew the first 30cm from the stored energy in the seed. Your soil looks very high on perlite or is that just a coverlayer? Perlite doesn't contain any nutrients.

If you have serious plans with the seedling then prune the tip and repot it.

Its a mix of perlite and some potting soils. As soon as the new growth hardens its going to be put into a larger pot. I'm hoping to see fruit from it in 2018 or 2019. (Eesh,I remember when disco was the thing in 1978 like yesterday,and now I'm writing about 2018.)

Sometimes people forget that a stubborn plant might need a shot of stimulating fertilizers to get going again.

i grew this from seed (Florigon)

comfrey tea, and fish fertilizer... It LOVED it !

it flushed like 4 times in a row, 2 sets of leaves at a time !

Oh yeah,that's a nice seedling. You're in norcal too?
I would think that's about 3 years old? THAT would be 3 perfect growing years- congrats.

Whats great about the small mangoes is you don't need to graft them to make sweet fruit.
Fish emulsion does seem to make a nice even green all over the plants. Its as organic as they come too! . Good thing the smell in the mixing can doesn't transfer to the ground..or very little.