I am 27 and going through the same thing, it seems no matter where I work until I can truly setup the structure or foundation for a project I never feel like I am working on something glorious because I think it wasn't put together well or sloppy; I have worked at places where I believe it was put together well so I'm not always putting down code I inherit. The way that I keep sane is I try to stay positive by going to meetups and being with other people who are excited about the more advanced things and have the same type of hunger for purpose. At home I also work on personal projects and explore new things and I would recommend that. I quit my job like you a year after the startup I was with was acquired because they really didn't care about the tech aspect of it and joined a new one but I am not really challenged (even thought they needed to hire a senior software engineer) and try to lose myself in my routine so the day goes by quick. I think what I am going to have to do for purpose is do more open-source projects or build small apps of my own. I would recommend that. Focus on your family too and your non-tech life, remembering how valuable they are in helping you not think of this. There are tons of us like you.