Copper T side effects. Implantation!

Doctor it has been 30 months of my marriage and i have 18 month old baby now me and my wife don't want any other baby for next 4-5 years we had planned for copper-t implantation regarding which my wife had a talk with  my mom as well as her mom but both are not letting us to do so. They are saying it's not good and it will create lots of problem lykwise excess bleeding, cramping, weakeness, weight loss etc Whereas i read i never found any issues except excess bleeding in some cases. So what we both do is it safe or not and what are complications with it?? We don't want any protection to use so is there any other way to keep pregnancy away?? Injections and contraceptive pills i think are not good option for long run and also my wife has to do lots of house work so bed rest in day is almost nil so going for copper-t is a good option or not and how tp convince both the family memebers