Text messages, using SMS, no data, with wifi

I recently ran out of data, so switched my iMessage off and turned off cellular data (send as SMS was toggled on). I was connected to wifi over the course of about 5 days. However, I still managed to miss 53 texts. Which came through when I turned my cellular data back on and received all of them. Many of these were group texts, but some of these texts were with non-iPhone users too. I had my partner start a new group chat (he’s an iPhone user) and I still didn’t get his messages with our mutual friends. I had to re-start the group myself and then I received their texts. I’m concerned if this happens again I will be unable to communicate with others.