Could I be pregnant?

So I have the copper iud and I've had it since my son was born 3years ago it says it last 5 years so I'm going by that and since I've been on it I haven't missed a period until this past month I was supposed to start last month on the 11th but nothing happened. And today I just started I'm so confused like could it be that it's implantation or a possibilitie of being pregnant or am I just trippin?