Web design and development services

I am a freelance webdesigner working with four online websites namely <a target='_blank' rel='nofollow' href="https://www.clasoo.com" target="_blank">Clasoo.com</a>, <a target='_blank' rel='nofollow' href="https://www.onlinekanyakumari.com"  target="_blank">Onlinekanyakumari.com</a>, <a target='_blank' rel='nofollow' href="https://www.adruz.com" target="_blank">Adruz.com</a> and  
<a target='_blank' rel='nofollow' href="https://www.speroh.com" target="_blank">Speroh.com</a> .
I have still not registered GST as my turnover is below 20 lakhs. But when i personally do a webdsign, customers ask for GST invoice and hence i think, it is better to take GST Registration on my opinion.