Avocado problem

[Lokoko]

Hi,
our avocado succesfully grew from seed but now the plant cant get more than three leaves. Every time the old leaves fall the new three leaves grow. We water the avocado twice a week and it is placed next to window. Is it normal or are we doing something wrong with the plant?
Thank you for your advices

[pineislander]

It is a tree which at first feeds from storede energy in the seed. Eventually that energy will run out. The pot is becoming too small, time to move up to 10 liter pot with nutrients and show it some heat this summer.