Is saying "I don't like my situation" considered among the forbidden phrases or an objection to divine decree?

Your answer to the question is not considered an objection to divine decree and destiny if you do not intend it as such. It is befitting for a believer to praise Allah and ask Him for well-being, and it is not permissible to show displeasure with Allah's decree. If a complaint is uttered, not by way of displeasure, then there is no harm in it, as happened with the Prophet, peace and blessings be upon him. Al-Hafiz Ibn Hajar mentioned that mentioning pain is not a complaint, and that what matters is the action of the heart, not the utterance of the tongue. Indeed, some scholars have even gone so far as to say that contentment with divine decree is not obligatory, but rather patience is.