"صَديقَتي is the feminine for صديقي and ذَكِيّة is feminine for ذَكِيّ

The previous response is accurate, but I don't believe it is answering your question. When a word is feminine, it has the "taa marbuuta" (ة). This will remain in this form until it becomes a possessive. Once you add a possessive suffix to the end of a word with a taa marbuuta (ة) it will turn into a regular "taa" (ت) and the suffix will come after. Hope this helps!