I have a final coming up in my baking class and decided to make macarons for it. However, I didn't realize how temperamental they'd be. I've tested the recipe so many times and so far my biggest problem is that my macarons end up with a huge air gap inside. I've tried 3 separate recipes and all of them turn out this way. They look good, but that air gap just ruins the texture.

I tried a French meringue method and a Swiss meringue method, but neither works. I've been using equal parts flour and powdered sugar. The flour is a combination of Almond and pistachio flour. The altitude I live in is about 5,000. My chef keeps saying that's the reason I keep getting air gaps, but she can't seem to help me figure out a way to make my macarons better. I know I'm not taking them out too early because they pull away from the silpat just fine. Is there anything else it could be? Are there specific change I should make to accommodate my high altitude?