I think Tim hits on a very good point. There are many variables involved. let's face it everytime humans copulate we don't have pregnancies.

For one females need to be in their correct cycle for it to take. Also 1 copulation is far from guarranteed. It seems you are doing everything correct. I always believe in back up snakes. Some people get 1 male and 1 female and think they are set. it only takes one of them to have a fertility issue or not have good breeding response and the project is dead in the water.

Patience is also a must when dealing with these animals, I find they do things when they are ready not their owners.

Best of luck, both your snakes are real beauties