No period for 6 months.

I had my last period 6 months ago. They are usually every 6-8 weeks. That's been normal for me since forever. I'm 22. I've had 2 children the youngest is 2.5 years old. Im not on any birth control. The last few months have been a mess. A lot going on so could be stress. I've also put on a bit of weight I'm weighing about 220lbs now. These are the only factors I can think of apart from a hormone imbalance but I obviously can't say as I haven't been to the doctor yet. I did feel like in June I was coming on, had all the signs I usually get. Didn't come. And then the same happened in August but it didn't come. I've spotted twice after sex in these 6 months but I think it was a case of to rough or something I don't think it's related. I've had no other signs or symptoms of anything. And I'm not pregnant. We use protection and I've taken many many tests. And to be honest I've not even thought about my period coming really. My life has been so all over the place that it didn't even register how long it's been until me and my partner got talking about it the other day and I counted back and realised 6 months is quiet along time with no period. I know the next step is to ring the doctors but I'm scared. It could be nothing or it could be something. I never have to go to the doctors ever for myself. The only thing medical that happened to me is having my babies. So this is a bit frightening thinking I'm going to have to do something about it now.

Have any of you experienced this or similar?