Unfortunately there isn't a true way to report on tickets that *you've* touched at any point in a certain time frame. The closest you can get, as I'm sure you've discovered, is to report on tickets where "Modified By" is yourself and then report on a date value like Created Date. Modified By is only reflective of the *last* person who touched a ticket, and so when someone happens to come later and "touch" one of your tickets it removes them.
Folks have asked for this capability, and I'd encourage you to add an enhancement request if this is a needed reporting capability. You can add an enhancement by going to the Home page of this portal and select the "Submit a Product Idea" button.
Sr Support Consultant, CS