Congratulations on already completing 5 classes, that's fantastic, you are building a new understanding of your body and working your body/mind in new and different ways. Building a solid foundation takes time so please don't stress or get discouraged and try and enjoy the journey... I know that can be annoying to hear but it's really true especially when establishing a body, mind, life practice.
Each person's experience is a little different as ever day life with work, family, etc. commitments effect our energy levels in different ways. It took me a few weeks to adjust to my practice, when I first started, and keeping a journal helped me identify food, sleep, hydration and stress levels so I could connect the dots with the days that I felt awesome and times that I didn't feel all that hot (no pun intended... okay, maybe a little intended) and then I started creating routines around those habits that led me to feeling my best.
Keep up your hydration, eat plenty of juicy fruits/veggies with the warm Texas weather still in full gear and whenever you feel tired try closing your eyes and taking 5-10 slow deep breathes and just focus on how good that makes you feel in the moment.
All your teachers and fellow students are here for you so keep communicating and enjoying the ride!