Combatting the feeling of pure rubbish

I have been working on a manuscript every day for over a year. I have a full time job so I am proud of myself that I made this commitment, feel called to do it, have secured a publisher and have pressed on through some significant life changes this year. Yesterday I printed it off and paged through it and had the feeling that it should be so much more than it is for all the work I have put into it. And a part of me thinks it will never be ready to send off. When I feel that way I hear one of the webinars about something being good enough and “B” work. It’s become such a huge part of my life and I believe it is the beginning of a new and exciting chapter that I am anxious to start. How will I know when to say it’s good enough so I can move on to my next idea?