This is my guppy having her fry. She had just started to drop. Try and get a static pictute and it will help. At her back end when she is about to drop you will see a while tube expand. My Guppy and Swordtail do anyhow. This means they are going to drop imminently. My guppy literally squares right off overnight and it is quite obvious when she is going to drop. I havent had my fish long but have had 3 drops from my guppy and caught her with all 3, and same with my swordtail the last two times I know she was going to drop overnight. So you will soon recognise the signs. Good Luck and I hope you catch her.
I just thought, what are you going to do with your fry. I noticed you have no plants or anywhere for them to hide in your tank? x
PS, soz dont know why my pics are tiny. Will try and upload them again later.