With high fsh your body starts to recruit follicles early (before af) and you can have a dominant follicle very early. I had an 18mm on cd 2! Unfortunately your lining would not likely be able to support a pregnancy (might work out if you were doing ivf and freezing). Have you had any b/w or ultrasound?
It's definitely possible. In December 2011, I had a 20mm follicle and a lining of 6mm on Day 6 and ended up ovulating on Day 9. That was the cycle I actually got pregnant (but ended up later miscarrying due to a chromosomal abnormality in the fetus). I agree with the previous poster that you should get bloodwork and an ultrasound. Good luck.