Ovulation question..

So my husband and I have been trying to conceive for about 10 months now. We had a miscarriage back in September, and we've been trying ever since. I noticed on my Glow calendar that it puts my fertile week the week right after my period which would be days 1-7 after my period. But my OBGYN told me that I ovulate anytime between 10-15 days after my period.. I guess I'm confused as to when I really do ovulate... I guess I could always by ovulation strips but that can get pricey. Help?!