insecure

Insecure describes someone who doubts themselves and needs telling they are all right. Checking three times in one evening whether a friend is annoyed with you; asking how the presentation went and not believing the answer.

In that sense it comes with about: insecure about her accent, insecure about the way he looks in photographs. The other half of the word has nothing to do with feelings — insecure also means not safe or not firmly held: an insecure ladder, an insecure job, an insecure lid on a hot drink. Computers took that thread as well, so an insecure connection is one that somebody else could read. The noun is insecurity, doing both jobs: personal insecurities, and job insecurity. Insecure is not shy — a shy person finds other people difficult, an insecure one finds themselves difficult.