Thank you for your help !:) I tried writing the formula in another way and got the one below, as attached. It's ethyl methanoate!
Here's what I found:
The general formula of esters is RCO2R', where R and R' are alkyl groups or aryl groups.
A homologous series is a family of organic compounds which have the same general molecular formula, follow a similar structrural pattern and have similar chemical properties.
So..since esters do have a general formula and have similar structural pattern and chemical properties, they are considered a homologous series...?