What can I do to make drawing this angle easier?
Here are some key differences I noticed between the reference image and your drawing:


The relative location of the pupils. If the subject is looking up at you, the pupils should be at the top of the eyeball, so there should be more white showing at the bottom of the eye.
The relative locations of the mouth/nose/chin. Since you are viewing the face from an oblique angle, the nose and mouth should be closely spaced and near the chin. The nose line will also seem longer than when faced head-on.
The position of the shoulders: in the image, her shoulders intersect at the level of her nose, about halfway up her face. In your drawing, the shoulders are at the level of the chin. Try moving them up.


The hair line looks good to me! At this angle you will see a lot more hair than usual, since you're viewing most of the top of the head.

Now for techniques: When drawing poses like this, I find it very helpful to sketch out a "wireframe" of the head. I use a roughly spherical shape for the cranium (pinched a little where the chin goes, like a rounded teardrop), then place the eyes on the equator line and the nose about 1/3 up from the chin. There are more "formulas" for these and other facial feature proportions you can search for if you're interested, but since your character is already stylized you can probably just eyeball the rest. (Sometimes I even use a wireframe method on the eyeballs themselves, if they are detailed enough! It helps me place and shape the eyelids as well as shade accurately.)

The neck and shoulders are probably trickiest to place. Remember that the neck connects at the back of the head near your ears, so when you rotate the head downwards, it will be from that connection point. That is, you're not just rotating the head-sphere around its center (and keeping it in the same position relative to the shoulders), you're flopping it forward over the shoulders.

Here's a very rough example of what I mean (sorry for MS paint.. limited options on my lunch break!):



The initial shape is black, guidelines are red, and features added afterwards are blue.

All that said, I strongly recommend finding reference photos as you have done here, and trying to copy them - not tracing, just studying as you recreate it. The suggestion in the comments to attempt the pose yourself is a very good one too! Many artists (animators, famously) keep a mirror at hand so they can check how a particular expression or pose looks.

And as always, practice makes perfect - as you draw more faces in more poses, you'll develop a better intuition of where to place features without needing to think about it as much.