You can’t add on device storage but you can add anywhere from 50gb up to a whopping 12tb of cloud storage with iCloud+ For a monthly subscription of course, but the 50 and 200gb options are pretty cheap and reasonable

If you’re using iMessage to send or receive texts and images/videos this could easily be the reason, especially if your friend and bf are using their default texting apps on Android.

If you and your friends all switch and use the same 3rd party messaging app (like WhatsApp), this should solve the problem on both ends.