Hi, Jolene!
Retrospective power analysis is generally an inappropriate thing to do. As @Georg implies, we know very little about your experiment. You designed it (without considering the power of the experiment?), ran it, collected the data, did an analysis, and did not achieve “significance.” So now you compute power retrospectively to see if the test was powerful enough or not. That is a specious question. We already know it wasn’t powerful enough to detect the effect size...that’s why the result isn’t significant!
Power calculations are useful prospectively for design, not retrospectively for analysis. You might wish to entertain modifying your hypothesis for a subsequent experiment to be one of equivalence or noninferiority; Please see the enclosed Hoenig and Heisey paper.
Without any understanding about your experiment's objectives, design, conduct, or analysis, the sample size seems quite large. You may be able to use the data from your experiment to formulate a simulation model to explore the prospective power for specific potential designs and analyses for a subsequent experiment. It seems to me that this approach would do the best job of answering your questions.
Good luck!