Maximum Heart Rate

Hey Fittit, 26m 5'7" 230lbs, recently started working out after spending most of my time after High school being fairly unhealthy. Currently trying to lose my extra weight and got back down to 180 at least to start. Currently using the Isogenics diet to lose weight, seems to be working at about 7lbs/month so far which is great, but I have a concern. I've read in a few places that my heart rate maximum should be something like 220 - my age and that exceeding 75% of that could be dangerous. Now that said my heart rate regularly hits 184-186 while I'm doing cardio. I don't experience any pain or dizziness, but I just want to be sure I'm not putting myself in some kind of danger?

I will be talking to my doctor at some point but I can't get in to see him for another month and a half, so i figured I would ask you fine folks.