Employers as LOR writers

[Lolita]

So I've been out of school for 4 years. I have one professor with whom I worked on my thesis writing an LOR for me. I planned on having my academic adviser write a second, but she said it is against her policy to write lors for students after years had passed. My second lor was from my department head where I taught English, and his was praising me beyond words. So, for my third, I need to go to the assistant principal who evaluated me when I first began teaching. Will it look bad that I only have one lor from a professor, or will it seem normal since I was out of school for so long? Also, I wrote extensively in my statement of purpose on how I struggled but excelled as a teacher and how that experience prepared me for graduate school. It seems fitting then that I have lors from people confirming that I did, in fact, excel as a teacher. Still, do you think I will be hurt by not having multiple lors from professors?