I already have a C1 level in German (Goethe C1); however, it is still very difficult for me to express myself in everyday situations. I suppose it has more to do with my lack of vocabulary.
To get a certified C1 level one needs to pass an exam (such as those administered by the Goethe Institute for German or Alliance Français for French, see also CEFRL). This would imply testing in four or five categories, including the passive and active skills:
- (structure comprehension)
Each skill is evaluated, but depending on the type of the test, one either gets a single level assigned (such as Goethe-Zertifikat) or separate grades assigned for each skills (such as DaF). In the latter case on can technically have disparate levels in different skills - (e.g., I was tested a few years in a similar French exam, scoring C2 level in passive French skills, but only B2 in written and spoken production.) However, in the former case (Goethe-Zertificat) one fails the test, if one is unable to perform in one of the categories. See here for the skills required to earn specific levels.
Thus, please take no offense, but it is not clear what you mean by C1 - perhaps the level of your German class... but this is not your real level - you need to revise what you have studied, do the speaking and listening exercises, learn the vocabulary, etc.