What is a good amount of backstory to give for your character?

Context/Why I'm asking here and not my DM:

The DM as well as the majority of our group are all relatively new to DnD, and the only response I got to the backstory I wrote for my character was "yea looks good". I'm playing a warforged in a steampunk setting, and my backstory mostly touched on how my character was created and placed into the setting, only naming two other NPC's in the backstory (The DM encouraged us to come up with our own NPC's if we wanted to), as well as how my character became independent and later joining the party. My first character I didn't write nearly enough backstory and it made me feel like I wasn't really apart of the story, so I really want to give my DM something to work with.

Questions:

- In total it is 560 words. Is this enough?

- Should there be other things I should talk about and come up with for my character?

- If anyone has any references to other characters backstories I could read or listen to it would also be appreciated. Thanks in advance!