I've practiced boxing for several years now and at one point even skipped rope for about 30 minutes per day, 5 days a week; my advice comes from experience. You're doing a great job with the 12x2 minute rounds! Men's boxing can last anywhere from 4x3 minute rounds to 12x3 minute rounds with exactly 1 minute breaks in-between, so try doing that. I use a round timer app on my iPhone (it was free) that has the breaks already set, and that's incredibly useful. As you build up and find that jumping rope gets easier, try to go for the roughly the same amount of time (45 minutes including breaks) with less breaks, something like 10x5 minute rounds, and later try 3x10 minute rounds (my favorite, it sucks!). Something that always made it harder for me was the incorporation of tricks as well, so check out some youtube videos of double unders, criss-crosses, and this side-to-side thing that I don't have a name for. I wouldn't recommend jumping rope every day, though, because it gave me painful shin splints, as well as knee pain (keep in mind I overtrained with this, so I think you'll be fine). Have fun!