Hopefully now that you are older, you will be able to take the time to research more about rabbit care if you decide you would like to have one for a pet again. It's always a good idea to first learn all the basics and know what vet costs could potentially be incurred. If you decide you may go down that road of rabbit ownership, let us know and we can direct you to further information so you can be properly prepared this time.
As far as mixed breeds go, a mixed breed rabbit is rarely just a mix of 2 specific purebreds. More likely they are mixes of mixed breeds that were also from mixed breeds. In other words, there could be a mix of so many various breeds going back the line that there is simply no way to tell. This seems to be the case with your prior rabbit. She was a "mixed breed." That is her "breed."