Email hacked via telephone number

Hi my mobile number has been fraudulently transferred to someone else. They will have accesss to my emails via authentication. I’ve changed my passwords. I think they may be forwarding my emails as I haven’t received any since my mobile number was hacked. I can’t check if any email rules have been set up to forward as I’ve changed my security set up to stop others using my number to access emails. This has now stopped access to my account! How do I know if my emails are being hacked?