See BIT (↑ bit )
DUBIOUS : 'An' is a bit problematic.
GOOD : 'An' is slightly problematic.
DUBIOUS : The instructions were a little bit confusing.
GOOD : The instructions were a little confusing.
DUBIOUS : My diet is a little bit different nowadays.
GOOD : My diet is slightly different nowadays.
BAD : Thank you very much for giving us a bit of your free time.
GOOD : Thank you very much for giving us a little of your free time.
A bit and a little bit are used mainly in informal styles. In other styles, it is better to use a little, slightly, rather, quite or somewhat : 'His brother was somewhat older than we had expected.'
BAD : I watched a little bit television and went to bed.
GOOD : I watched a little television and went to bed.
GOOD : I watched a bit of television and went to bed.
Use a (little) bit before adjectives: 'She looked a bit tired.'
Before nouns, use a little or (in informal styles) a (little) bit of : 'He could do with a little help.' 'He's been a bit of a nuisance recently.'
BAD : He is a little bit too short to be a policeman.
GOOD : He is a bit/little too short to be a policeman.
GOOD : He is slightly too short to be a policeman.
BAD : The speech was a little bit too formal.
GOOD : The speech was a bit/little too formal.
GOOD : The speech was slightly too formal.
Use a bit/little too or slightly/rather/somewhat too (NOT a little bit too ): 'She is still a bit too young.' 'The pears were a little too hard.' 'The basic salary is rather too low.'