Gst collection

i Ihave regitered my name under GST and got the registration Number.My Turnover( Service - Chartered accountant) will be less than Rs. 20.00 lakhs only. My previous year turnover also was less that Rs. 10.00 lakhs.But for safer side I ahve regitered my name under GST.

Now whether I have collect GST for my profssionla fees

or can I raise the bill with out charging GST.

Is it obligatory to file monthly or annual return?

Suppose if I send my Professional Bill to my clients who are registered under GST and collecting and paying GST..

In that case any reverse charge mechanisam (RCM) will be applicable for my clients.

Kindly clarify

C.A.K.PALANIAPPAN