Whenever you're tempted to complain about things here, remember that DL is free, and that it's healthier to be grateful. :)
Sorry, don't mean to lecture, but I took a different free, online language course - which is no longer around - that actually taught wrong usage, so I really appreciate DL's pretty excellent and very effective instruction, and I want to encourage them to stick around. I hope you'll join me in this sentiment, and phrase your questions with a more positive tone.
I think you would have to tell from the context which is meant. You don't need a gender or number marker on sentito because you're using the auxiliary verb avere rather than essere and you don't have an apostrophized object pronoun like l'ho sentita. Anyway, it wouldn't take the gender of the subject. You could say Io non ho fatto niente whether you are male or female.