I'm not entirely sure to be honest. I wouldn't have thought that it possible to ovulate during your period but if you are having long bleeds then it could be possible, but a 2 week bleed is extremely long, if this happens regularly then I would ask your doctor again, you shouldnt bleed for longer than 10 days.
Have you tried ovulation tests? They can be abit mire reliable than charting (if you want to try something else especially to confirm any patterns).
I have also charted and seen that sometimes when I have longer periods my ovulation falls during the last day or two of my period. Is that possible?
Yes that sounds about right. If you have a 28 day cycle then you will most likely ovulate around day 14, your fertile period is generally between day 10-18.