It's hard to guess exactly what you did wrong, but one way or another there was no development at all. No matter what your camera did, you should still see exposed leader and frame numbers. Totally blank film is not the result of merely expired developer or a bit too little developing time. At 8 minutes and 86 °F, something should have been visible, even with very exhausted developer.
A number of mistakes could lead to this same result. You could have poured in water instead of developer. Maybe you flipped the fixer and developer. The bottles could have been labeled backwards. You could have messed up mixing the developer in the first place, like forgetting to include the actual developer and accidentally ended up with only water. Maybe the developer was neutralized by getting a significant amount of fixer or stop bath into it last time.
Open your developer and fixer bottles and smell them. They have a quite different smell, although if you're not used to the difference you may still not know which is which.
Put a few grains of baking soda on a piece of glass or something inert, then add a drop of chemical. Do this separately for each of your solutions. The stop bath and the fixer should cause bubbling. Nothing interesting should happen with the developer.
Rub a drop of developer between your fingers. It should feel a bit slimy, like soapy water does. The stop bath and fixer will not feel slimy. Make sure to rinse and wash your hands afterwards. You shouldn't generally touch these chemicals, but a drop for a few seconds won't cause any trouble if you rinse properly.