I would definitely followup with your OB/GYN. Something certainly has changed.
I have to say my cycle totally changed after having our son 12 years ago. I had a lot more spotting between periods and they became more unpredictable timing-wise. I became more moody and tired which, along with other symptoms, pointed to thyroid...but that was fine, like yours.
Your BC pills and IUD could be changing things. You might want to talk with your doctor about whether or not any of that should be changed.
Also, any chance of an infection or polyp? I was hospitalized two different times in the past year for an abscess in the fallopian tube and ovary. They caused a lot of spotting and pain when they were at their worst. One side was removed, the other was controlled with antibiotics. But we suspect I was living with some sort of infection for years in my internal cavities. It wasn't any kind of STD, just some weird infection. Unfortunately, they didn't identify what the specific cause was.
If you've got the moodiness, that sounds like hormonal imbalance of some sort. (You're too young for this, but I have two close friends who went through menopause in their early to mid-30s! So anything is possible!)
Any vitamin deficiencies like D or anything else?
That's about all I can think of at this point. Good luck and let us know if you come up with any answers.