Does it make sense to say 我个心? I suppose its meant to be 我的心. I still cannot distinguish when to use it. Maybe it to do with the fact that I am a Cantonese speaker?
It totally make sense to say 我个心 colloquially in spoken Cantonese.
我的心 is used in Mandarian or formal written Chinese.
Moreover, 个 in 我个心 is not really used as a quantifier in 我个心
个 in 我有一个心 can be used as a quantifier, but it's not a common usage, every one has one heart.
个 in 我个心 here, is the same as 's in "I's" or My in English
so both 我个 心(Cantonese) or 我的 心(written/Mandarin) mean my heart
我个心 does not make sense. I guess you're confusing 个 with 嘅.
我嘅广东话讲得好唔好 => 我的广东话说得好不好
个(quantifier) pattern：number + 个 + noun
when used without a number it normally just mean one：
我有个朋友 => 我有一个朋友
的(particle) pattern：noun/pronoun + 的 + noun
个 is the simplified version of the traditional character 個.
個 is a classifier for many objects including 心 in Cantonese. '
Example: 你個頭，佢個胃，我個肺 (your head, his brain, my lungs)
The Cantonese phrase 呢個心 (this heart) in Mandarin would be 這顆心
The Cantonese phrase 我(呢)個心 (this heart of mine) in Mandarin would be 我這顆心
The Mandarin 我的心 in Cantonese would be 我嘅心