Q.growing lemon tree
Hi, I started lemon tree from organic lemon seed, have it growing since December 2016, looks fine but it is very tiny is it normal, when will it form as a tree? do I need to do something, it is indoor, in the pot about 5 inches

For being only 4 months old, that lemon tree looks great! It will take quite a few years for it to reach "tree" size, and even longer for it to produce fruit. But in the meantime, you will see it get bigger and bigger. Make sure it gets at least 4-6 hours of sunlight per day. When it gets a little bigger, you'll want to repot it an move it away from that smaller seedling.
You can read more about growing lemons from seed here:
https://www.gardeningknowhow.com/edible/fruits/lemons/propagating-lemon-seeds.htm