Ovulations are pretty obvious the trick is they could only last a few hours so they can be easily missed and lots of times you catch the begining or the tail end where they look swollen but not as extreme as you may have heard.
Here is a pic of one I caught dead on and there is no mistaking it
Here are a few I caught not at the largest point but still obvious to the experienced eye.
You will see the belly scales look like they are getting pulled up around the sides and the scales themselves looked stretched apart. Most snakes have not eaten in a while at this point so if they look like they swallowed a huge meal and that one area look so much larger than the rest thats a good sign. Sometimes I start to see them come and check every couple of hours(if I can) and then you catch it at its peak. Once again it doesnt last all that long so it is missed if you arent constanly checking for it.
Hope this helps.
i saw my het pied ovulate, the ovulation from my bigger girl was not as noticable