Can we watch the Ovas and movies entirely after the series?

Can we watch the Ovas and movies entirely after the series? Because it is too furstating to find out the real order to watch and also that I just have found about the ovas and movies and already have moved on to s3 ep1. Now I don't remember every single small story piece so if I watch an OVA, I'll get confused and will have to watch the episodes again where the OVA happened to recall every small story piece. If we cannot watch it after the series then can someone help with order? Thank you