Nexplanon and sporadic periods

Emilee
So I've had the implant since last April. When I had it put in I didn't have my period for a couple weeks and then I had it for a complete month. Then it became normal, it would last about 4-5 days. But at the start of this year I've been having longer periods that would last about two weeks and then stop for a couple days to a week and then start another two weeks. Lately my periods will be for a couple days and then last two or even three weeks. I don't know if it's normal to have that bad of an irreagular period or if something else is going on. Last time I went to the gyno I asked her about it and she said it was normal. But a couple months or so ago I was feeling nauseous all the time and I was always tired and I felt like I was having symptoms of pregnancy, so I took a bunch of pregnancy tests and different brands and they came up positive, I mean the second line was faint but I asked a friend who was pregnant again and she said that even if it's faint it's positive. I don't think I went to the doctors to make sure if I was or not I just let it ride through. I did get my period right after. But it was really weird. 
So anyways is it normal to having that many periods in a month or is something else going on?