In your query you must include the quotes
'value' => '"'.$dev_id.'"', // matches exactly "123", not just 123. This prevents a match for "1234"
In your loop you actually need to count the totals for each selection, I’m not 100% certain this will do what you want.
$counts = array();
if ($doctors) {
foreach ($doctors as $doctor) {
$value = get_field('bedrooms', $doctor-ID);
echo $value;
if (!isset($counts[$value])) {
$counts[$value] = 0;
}
$counts[$value]++;
} // end foreach
} // end if
echo array_search(min($counts), $counts); // min
echo array_search(max($counts), $counts); // max
