Just think about this. You've asked do you have a moment of doubt (about what?) or a bad day after manifesting your desires. Everybody has a moment of doubt about all sorts of things, it's normal. I had more than a moment of doubt about the interview for this job I have "I am sure they will want someone better than me" but they didn't and I was offered it.
I wanted a car, similar to the one I had to scrap. I got almost an identical one, so I manifested it, and quite quickly too. It is sitting outside my house, and I have had a few "bad days" since then when things haven't gone right, for example, it has rained all day today and I forgot my umbrella, the bus sailed past and didn't stop (I don't take the car to work) and it made me late, things like that. Does that mean I have to start all over again, or someone will steal my car, it will be in an accident, or something?
Is that what you are asking? Because I think you are worrying too much if so.