I think a problem with your question is that it comes from a very Westernized cultural point of view. I don't know the exact situation with your senior, but Japanese people don't like to publicly speak openly about negative feelings and blame, so more often they thank people. Therefore personally I would say something like,
Thank you so much for always saving/helping me recently.
Of course, as I don't know your situation this might not be true, it depends on why you've been annoying and your relationship with them. You can always change the verb to something more appropriate.
As to the translation you made, I think if you said this to most Japanese people you would make them feel uncomfortable (a big no-no in Japanese society). This is because you are saying very negative things about yourself and they would feel the need to tell you not to worry, etc, so it sounds like you are fishing for compliments. Further, you are not directing your nuisance towards someone, but giving yourself a general negative trait (lit: I am an annoying person).
The phrase for being a nuisance to someone in Japanese is 迷惑をかける, so you could use this in te form with an apology. However, culturally Japanese people expect actions to make amends, so I would definitely follow it up with some sort of plan on how you won't be a nuisance in the future (これから...頑張ります。). If your senior is really Japanese though, you would probably want to stick with the first idea of thanking them.