unsure

adjectives

lacking self-confidence
"stood in the doorway diffident and abashed"; "problems that call for bold not timid responses"; "a very unsure young man"
diffident, shy, timid, unsure
lacking or indicating lack of confidence or assurance
"uncertain of his convictions"; "unsure of himself and his future"; "moving with uncertain (or unsure) steps"; "an uncertain smile"; "touched the ornaments with uncertain fingers"
incertain, uncertain, unsure
antonym
sure