One persistent idea about classical musicians is that they simply are some kind of copy machine, doing exactly and only what is written in the score. However, this is far from reality, since the score written by a composer is only the starting point of a musician's journey to come up with an interpretation of a piece. During this process, a musician basically decides how a note written on paper is going to sound like. The score acts as a blueprint of a piece, but while it can contain a lot of information, there are still many blank spaces and ambiguities. For instance, often dynamics and tempi directions are not extremely specific, leaving space for interpretation. This way, the composer gives the musician an opportunity to be part of creation process him- or herself, while being guided by the score. This is also the reason why the same piece played by two different musicians can result in two completely different recordings; they interpreted the blueprint differently.
There is not really one right interpretation, there is only an interpretation
'But wait a minute, how do you make those kind of decisions?' Great question! Well, to begin with, there are often certain stylistic ideas which were common at the day and age when the piece was written which can give you hints about how a composer intended a piece to sound like. You can learn about these ideas by reading the letters or treatises of important musical figures of that time. But even then, there are probably still many variables which are not discussed in these sources, often because the composer expected the musicians of those days to simply know certain 'rules'. So, what is next? Who can we trust in our search for the 'thruth' (if that even exists...)? This is where we find ourselves in a bit of a grey area. I have experienced how two famous and respected musicians tell you that there is only one 'right' way to play a certain piece, but these ideas turned out to be completely the opposite of each other. This taught me that there is not really one right interpretation, there is only an interpretation.
Do what you believe in, that way you will always be convincing
Relying on others sometimes helps, but it can also make you more uncertain. In the end you need to get confident in making your own decisions, coming up with your own ideas. This can be based on an article that you read which discusses the composition, by analyzing the piece itself, or by playing other works written by the same composer which can give you a better understanding of the style of the composer and thus of the piece you are playing. But most importantly: you have to do what you believe in, what feels right to you, because that is the only way you can make sure a piece really comes to life and has meaning, which in turn can inspire your audience. So don't be scared to make your own decisions but instead be excited to share the beauty you discovered in a composition with your audience!