هل هذا (رقـمُـكِ) يا مها
the diacritics are displaced here ... "M" must have Dhamma (U-vowel) and the Kasra (I-vowel) should be under the last consonant (K) because it's dedicated to a female (Maha)
So the pronounciation will be like what? Raqamuki? I don't quite understand why because we've been taught that the possessive article goes like -ik or -ak for every word. Is that generally wrong, is this a difference in Arabic depending on the region or is this word an exception? I am really confused as I see comments saying 'this is wrong' all the time.
The varieties you've mentioned are dialectic variations, used mainly in Egypt and the Levant. Standard Arabic is not like that. In Standard Arabic, it would be Raqmuka to a male, snd Raqmuki to a female