The phrase "I'm not bothered" is a colloquial expression used to convey a lack of concern or interest in a particular matter. However, there are several other phrases that can be used as synonyms for this term. These include "it doesn't matter to me," "I'm indifferent," "I couldn't care less," "I'm not fussed," and "it's all the same to me." Each of these phrases conveys a similar sentiment of nonchalance and lack of interest. So, the next time you want to express that you're not bothered about something, try using one of these alternative phrases to add some variety to your vocabulary.