Messages and Contacts disappearing

Hello, I have had my iPhone 7 Plus for 9 months now and in the last few months I have had trouble with message notifications not coming up on my phone as well as missed calls not showing. It will tell me that I have a voicemail but not that I have a missed call or who it was. My contacts keep randomly disappearing as well which is extremely stressful as it includes the contacts of family members or work contacts and I have no way of finding out exactly which contacts have disappeared. I have tried to toggle on and off iCloud backup for contacts and it has not worked at all. Any suggestions? I never had this problem with previous iPhones that I have owned that I did not use iCloud with. Is iCloud worse for memory?