Help urgent!

Angel • Baby Number #1 08.Dec.2018👶🏼🌈❤️🇬🇧 Due March 2020💗💙

How do I know if a test is out of date? It was made in 2015 and the date just says 09/2017! It was wayyy reduced which is why I bought it but now I still think I'm pregnant I still have signs 🙄🙄