Hiya Dom! That's absolutely a valid concern. Once you're ready to reach out to agents/publishers, it'd probably be a good idea to private any of the chapters you've posted here. In my opinion, I see nothing wrong with getting feedback on earlier drafts in the meantime! I would check out our Copyright Policy if you haven't already.
John 14:27 Peace I leave with you; my peace I give you. I do not give to you as the world gives. Do not let your hearts be troubled and do not be afraid.