OH YES. When my seams aren't straight or no matter how hard I try its just not neat enough. I have thought about stopping altogether. But like you I have a loft full of fabric and a lovely sewing machine (well a few actually). What i do is stop. I might put it all away for a day or two.
I think about why I sew and what I enjoy about it. Sometimes its just working in fabric and making things for others, sometimes its to challenge myself that I can do this.
all I can say is ask someone to show you or help you. If you can post some pictures and ask for advice on QB. I have found this site so helpful. If we don't challenge ourselves with something hard we will never improve and advance our skills. And remember this is a hobby if you are not enjoying what you are doing stop that project. do something else and you might come back to the original one - you might not - it does not matter. Just enjoy what you are doing and do what you enjoy. Please don't give up