There are a number of resources online that can help you to decide which level of the JLPT is most appropriate for you.
This Japan Foundation page has sample problems from each level.
You can also find a “can-do” list for each level of the JLPT here, which will tell you what learners are expected to be capable of at each level of the test.
This level summary also outlines the linguistic competence assessed for each test.
This website, which is not affiliated with the Japan Foundation or the JLPT (meaning I can’t vouch for its accuracy), has some sample tests for each level.
Of course the best way to judge is probably to ask your Japanese teacher, but if you are studying on your own, hopefully one or more of the above resources will help you to get a sense of where you stand.