Thanks for your query.
Normally, during the menstrual cycle, one follicle called the dominant follicle grows in each ovary, and during ovulation, it is released and gets fertilized by the sperm if pregnancy
has to occur.
In your case, till the 18th day, there was a dominant follicle ( the larger one on the right ovary ) seen, and then on day 19, when it was not seen, that is when it had ruptured, as a result of ovulation.
Endometrium means the uterine lining , which is 11 mm, which is good growth.
Normally ovulation occurs around day 14, in your case it was slightly late.
All the best.