Bootstrap is bloated and identifiable within a second of opening a webpage, it's eventually removed from every project that goes anywhere. But it's a slow and painful process, because it has hooks in all over the place.
It's better to start out with some very simple css boilerplate, the app is new it doesn't need to look like Twitter... if the app is new it probably shouldn't look like Twitter anyway, it's current-year.
Someone set up a hot or not style web app that asked whether the screenshot was of a bootstrap site or not. It was harder than you give credit for, and interestingly it was hard both because many Bootstrap sites don't look like stereotypical Bootstrap, but also because many non-Bootstrap sites do look like stereotypical Bootstrap.
It's better to start out with some very simple css boilerplate, the app is new it doesn't need to look like Twitter... if the app is new it probably shouldn't look like Twitter anyway, it's current-year.