When using "I'm afraid" to express " I guess" , it is not 「我驚」but 「我怕」，and the 都 particle is not the right one,
The sentence should be 「我怕你唔敢噃！」( I'm afraid you wouldn't dare) the particle 噃 empathize 唔敢 and express contempt, imply challenge.
** 「怕」shortened from 「恐怕」「afraid」
「恐怕凶多吉少」- "( I am) afraid it is doomed." = " I presume it is doomed"
The sentence should be 「我怕你唔敢噃！」( I'm afraid you wouldn't dare) the particle 噃 empathize 唔敢 and express contempt, imply challenge.
** 「怕」shortened from 「恐怕」「afraid」
「恐怕凶多吉少」- "( I am) afraid it is doomed." = " I presume it is doomed"