4 months is still baby hair... in know that for most Yorkies it takes 2 years to see what their full adult coat will look like. Layla will be 2 in March and she never lost her puppy colors.. she is still black and tan.. no silver in sight... so dont' worry if you never get that full coat.... some yorkie sjust have fine hair... but hold on. i'd give her a year
i'd LOVE to see pictures!!!