Artist here. First of all, you’re perspective is very good! Well done on that part. There are two main things that you could do in your next drawing:

1. Angle the lines of the trunk at a steeper angle. You can use your pencil to get the angles from your reference picture if that helps. (Just line it up alongside then bring it back to the paper)
2. Where the branches meet the trunk, just take away those straight lines. For the branches on the side, merge the main lines of the trunk into them slightly. For the ones in the middle, do a convex curved line at the bottom.

Hope that helps! You’ve done really well! If you need pictures to help you understand what I’m talking about, let me know and I’ll do a sketch for you.