Based on your chart CD19 is a possiblity, but it is too soon to tell. Which days did you have a fever?
All my fever days were right after my period. I was out for a week with the flu - 3 days of which I had fever and one day where I wasn't in fever range, but I was still high. So basically most of my pre-O days were spent being sick. My post O temps are usually 36.7 or 36.8 and it's not unusual for me to have a couple days right after O where I'm not quite that high yet, which is why I think day 16.
I'm assuming those days are CD 6-9, where you have missing temps and an open circle. Even with those bad temps, I would still expect to be able to see a temp shift if you did O on CD 16, which I don't. I still think CD 19 is a possiblitlity.
I think OPKs would really help your chart, since they give you a little more info on when you might be ovulating.