is yoga really relaxing?
Depends.
In my case, when i first started doing Shaja Yoga, it was so fucking relaxing and peaceful, but then it turned out that those guys were trying to make us worship to their leader called Shri Mataji. And everything they said and done were always so very polite that you could never tell why the hell they kept saying "say thank you to Shri with your inner voice for all the beauty she has created, she indeed is a supernatural and superhuman being look at the brightness in her face, put her picture in your favourite place in your room and decorate there with beautiful flowers,fumes and candles, and each time you see the picture bow down and express your thanks to the one who contains the soul of god inside her human body." between the lines and during the meditation sections.
I told them that i did not want to put her picture in my room, not that because i had doubts, only because i dislike seeing pictures in my room because they cause me to have nightmares sometimes. Anyway, the instructors showed a very exaggerated response, they told me that if i would not put her pictures in my room, then i didn't have to practice the meditations. And i told them to fuck off
Surely yoga is supposed to clear your mind and relax, but it doesn't have to mean you'll have to pray for/worship at some woman who is surely an ordinary human being.
So, to my humble advice, you should try to find somewhere which doesn't aim to make you things you don't want to. Because, proven by experience, there are many religious groups which call themselves as yoga schools.