Implant troubles!

I've had the implant for almost six months and it's been rather annoying! My period has been so irregular just as an example in the last three weeks there's been 5 days where I haven't bled/spotted and the five days weren't in a row. 
It's been like this since I got it in, with one regular cycle then went back to being crazy. The doctor said its normal but it's taking a toll on my energy levels (iron levels are so low and never have been before) and it's affecting my sex life. 
Any advice will be helpful!