This is such a pity - I really like your cmposition and colours, but as you say, the focus is off. I don't think it's your shutter speed - the blur is too consistent across the shot for that. Two choices really I guess - widen your DOF with a smaller aperture (which I never do, don't like my portraits sharp from front to back!) or sort the focusing.
For my self portraits I do one of two things. If I'm shooting in less than great light where the auto focus struggles then I switch to manual focus and sit something in the shot where I'm going to be sat - my camera bag, a tripod, anything really. I then manually focus on that before getting myself in to the shot. That way you you don't risk it refocusing elsewhere. the other option is to leave the camera on AF and move the AF focus point on your camera to one that you're certain your body will cover when you're in the shot. It's always hit and miss with self portraits I find, and I waste plenty of shots taking, adjusting, retrying!
I'd really consider re-trying this shot, because I think it could be really good if you got yourself sharp and threw the heather well out of focus.
Hope that helps