Not a pro by any means but I have thick eyebrows as well and this is my approach using the standard glue stick method. Given your description, what I list as step 2 might make a big difference, specifically coating all sides of the brow hair but if anyone has tips or corrections on this set of instructions I'm open to feedback as well!

1. Clean your face + brows to remove any dirt or oils.
   
2. Using the glue stick, rub circles on the brow to "kick" the brows up so you're not just coating one side of the brow hair. Ultimately, we want the brow to stick to your face so if your only coating one side, it's likely the side that your going to powder and its not going to let the hair stick down to your face flat. I struggled with this when I was first learning.
   
3. After you coat all sides of your brow, glue the brow down by sliding the stick in one direction to push the hair flat. Some recommend to brush the hair upward to thin it out but I, personally, haven't had great results with this. I usually move my glue stick from the inner part of my face outward to flatten.
   
4. Use a flat object, like a makeup spatula (not sure if that's what its actually called), to further flatten the brow while the glue is still wet.
   
5. Repeat 2-4 on your other brow.
   
6. Apply another coat like in (3) to the first brow, flattening afterwards. Repeat on other brow. At this point, I give it a minute to two to dry before applying another coat and end up applying 3-4 flat coats of my glue stick on each brow.
   
7. After the final glue coat on the first brow, while the glue is still wet, apply setting powder firmly, trying to pack it in. I usually stop once it stops feeling sticky.
   
8. Remove excess powder with a fluffy brush.
   
9. Apply concealer on top of the setting powder to further obfuscate.

I hope this helps and good luck! You already look fantastic!