Should I use a comma in the below sentence? which one would be correct?
I am _ years old, and my birthday is...
I am _ years old and my birthday is...
I am not too sure about this, any help would be appreciated.
What would you need a comma there for? Commas are used in situations where you are listing things (for lists of things, in other words). What that means is that you would only need to use a comma in a situation where there are more than two things to talk about. And as far as I know, from a grammatical point of view, two items are not considered a list. So, this means that this use of a comma does not apply to the coordinating conjunction and because it's only used to connect two things together which is not enough for a list. For example:
I and my father went fishing yesterday.
I and my father is not enough for a list, therefore there should be no comma before and. That's why there should be no comma in your example either:
I am 28 years old and my birthday is 25.
However, when it comes to a situation where there are more than two items to consider—then, we're dealing with a list. And in that case, believe it or not, it's almost always optional to put a comma before and. This phenomenon is known as the so-called Oxford comma (also called a serial comma). Thus, the following two examples are both valid English:
I, my brother and my father went fishing yesterday.
I, my brother, and my father went fishing yesterday.
I am 28 years old, my brother is 25 and my father is 59.
I am 28 years old, my brother is 25, and my father is 59.