Every writer here has had exactly that same issue. We craft something we think is really good, then we take a step back, usually with the help of a beta reader or writing group or somewhere like Critiques, and we realise that what we've written is just the beginnings of something good and a lot more work is needed. That realisation isn't always easy to accept, but it -- and the commitment to improve and learn -- is vital if we're to progress as writers. So congratulations on passing that first milestone!