Yes. Unfortunately, the onus is on you to prove what you are worth. That is why I say you need to have an example ready at hand for every reason you are deserving of a pay raise. You need to demonstrate why you are valuable to the team and firm. What do you bring to the table persay.

Do you get formal reviews? These are a good starting point as you can pinpoint where you have improved (provide examples). If they don't give you reviews, which seems odd, this is also a good starting point as you can ask for one. Take opportunity then to address each point you feel you are owed a higher score in, again offering up examples to demonstrate why.

Research what the pay expectations are for your position elsewhere. When you are asked what you feel you are worth point this out and again offer up examples.

When did you last get a pay raise? Is there a pay structure in place? Are there other benefits you would be willing to take in lieu of money? For instance, would an additional week's vacation be a suitable compromise?