Struggling to hear the difference between epsilon and eta in my recordings

I’m a pronunciation-focused learner, and every time I record myself reading Greek texts, I can’t tell if I’m actually hitting the vowel length correctly or if my ears are just playing tricks on me since they sound identical. Does anyone have tips for distinguishing the two, or a way to use Chickytutor.com to get specific feedback on my vowel quality before I develop bad habits?