It is most likely a bit of every thing but more some than others. 38lb at 30" draw length should get you to 100yds if, and it's a big 'IF', your eye to nocking point distance is not too small. I can reach 100yds with 34lbs on the fingers and 29" draw length using C1s. ACEs make it easier.
I know you need heavier arrows at longer draw lengths but the gain in draw length normally offsets the arrow weight. That is you store more energy at 30" than someone drawing 28" at the same draw weight
My first point of call would be the anchor. Are you side of face or under chin? If side of face try under chin. If already under chin are you using a shelf tab? If shelf tab try increasing shelf height. I have even put my thumb on top of the tab shelf when shooting a fixed shelf tab.
Are you using clicker? If not are your arrows too long? You only need an inch over the rest. If not using a clicker you may be losing draw length when raising the bow if you raise your bow arm instead of tilting at the waist.
Next... drop to 80/90 grain points.
Next... you don't mention how close above the arrow is the sight pin? You will need about 0.5" to 0.75" above the arrow to avoid contact. Most sights allow you to drop the elevation scale.
Next... what fletching do you use on the arrow. Small fletch with 0.5 degree offset is more than enough. Large fletch with big offset will kill light weight arrow distance.
ACEs may help with 80grain points. You could try borrowing some or buying one just to try.
Finally... a clean release will also help.
Good luck.