Technically you have Endo's on lock. If you start to roll endo's then you're doing a stoppie or a front manual in BMX terms. Now that I am done being an asshole... You need to practice, practice, practice....

Start with a little more speed than usual and just keep upping your front brake pressure till the rear wheel starts to come up. Just practice getting it to come up a little and roll it out. You DON'T want to lock and pop at the end.... this is how you're gonna end up flipping them....
Good luck and take it in small steps.