How do you handle this all too real situation? Don't give up. Sometimes as a writer you will have uninterrupted times to write and at other times you may feel you never have the opportunity at all. One way to deal with this is to set an amount of pages to write for every time you do get a chance to write. If you only get 5 days out of the month set a 5 page limit, and that will result in at least 25 pages written for that month. The great things is if you are able to write more than the 5 pages, keep going and let your creative juices flow.
I want to make a note here, this is a time just to write, not edit. If you edit at this time your page output will be a lot less. I find if I am able to write, I don't want to stop that flow, just let the ideas and creativity flow. Yes, it might not be grammatically correct. Your sentence structure may be off. The key for right now is idea transfer; from you to the paper. Just keep writing!
~You don't think your story/idea is good enough. If you wonder about your story/idea being good enough or concerned if anyone will read your work, you are not alone. Any writer would tell you they go through this from time to time; some more than others. Your ideas/stories are important to you therefore it is hard to be unemotional about whether others will accept them or not.
How do you handle this all too real situation? This is where your will have to learn to encourage yourself. I think this is the reason why it is important to write an initial story sheet. Your story sheet is in the sense your "resume" about your story. You begin by writing your title or potential title. Give an introduction. In your introduction give as much detail as you can to try and convey your story. Some things you should ensure are present are: What do you hope the outcome will be for those reading your story? How do you want what you are writing to impact your reader? What do I need to say and how will I say it? Then list the sections and/or chapters giving them a title, even if you change them later. This is helpful when writing because you can always go back to this story sheet to make sure you are not getting off track. Taking the time do to this work ahead of time will also help you to flesh out your ideas, which can help you to feel more confident about your work.