iPhone 5s isn't receiving all text messages...??!

This is getting so frustrating. I have an iPhone 5s and it's not receiving certain text messages that are being sent to me. I've tried everything. I've switched the toggle off and on. I've reset network settings. I've restarted a million times. I've even deleted tons of content on my phone even though I haven't gotten any notifications saying I was running out of storage. Does anyone know what's going on? Anyone having this same problem? One of the people I'm not receiving texts from has a google nexus. We haven't had any problems up until the last couple days. Could it be the recent software update? Please, PLEASE help. I've missed out on several important conversation 😟