Depends. I've seen different kinds of time travel portrayed. I don't know if there's an actual name, I'd call it meta-conscious and endo-conscious.
Meta-conscious is the most common portrayal, and that's when you go back separately and you can exist anywhere in time, even existing in addition to your past self.
Endo-conscious would be when you go back in time to any point in your life, but only your consciousness goes back. You would take control of your body at whatever point.
So, if you were using meta-conscious time travel, you would be 10 and your younger self would be 3, and 7 years later, you would be 17 but your younger self (before time-travelling) would be 10.
If you were using endo-conscious time travel, you would physically be 3, but usually it is portrayed as keeping your memory and all, so you would be mentally 10.
Have fun :)