insecure(NOT CONFIDENT)
self-conscious(NERVOUS)
SMART Vocabulary: related words and phrases
Shy and modest
aw shucks
backward
bashful
bashfully
bashfulness
humility
inadequacy
inadequate
indoorsiness
indoorsy
mousy
reticently
retiring
self-conscious
self-consciously
self-consciousness
shyness
unassuming
wallflower
withdrawn
inhibited | American Dictionary
inhibited
adjective
us/ɪnˈhɪb·ə·t̬ɪd/
not confident enough to say or do what you want:
The presence of strangers made her feel inhibited.