Hi honey, don't worry about asking this, all questions are good questions if they are troubling you.
Unfortunately I can't say with certainty that the 18 month regression won't affect your LO, but I can reassure you that it's not all bad with all children. I think my DD did struggle a bit with it, but most of our troubles were around the 15 month mark which coincided with dropping to one nap and starting at nursery so lots could have been due to those changes. We'll be here to help you if her sleep does take a backwards step though. ((Hugs))
I too suffer with anxiety about things relating to my DD and have done for a long time even before she was born. Have you spoken to anyone professional about how you feel? If it is a big worry for you, there might be some medicines that could help and/or other talking therapy support out there. I only say this as I have found these things helpful, over time.