Serious Concern! You'd think this was my first!

Hi!! My name is Sarah!!
My husband & I have 4 amazing children. 6, 4.5, 2.5, & 5mo!!

I've never been 'regular'. Especially after birth.
My last 2 children were conceived without menstrual cycle!! The drs & midwives were SHOCKED. BOTH times.
Due dates were wacky & it was a mess.
My son was conceived with a script of Provera. He's 5mo & I've never had a period.
My husband & I don't practice contraception & at 2am, I pottied & there was pink spotting.
I got super excited, assuming my body was trying to regulate!! Maybe even give me a period!!!
When I woke up for the morning, the spotting was super light, & brown. Barely there kinda spotting.

I mentioned it to my husband & he brought up the night we didn't pull out about 7/8 days ago(last Sunday, I think). He's now SWEARING its implantation.
Granted I had a couple of drinks last night, I don't know if I would have felt anything. Cramp, wise.
I've gotten implantation spotting with 3 of my 4 kids. Some had cramping, some didn't.

I know the obvious answer is to wait & test. But I'd like some outside opinions on my situation.

Could this be implantation?? Or just a freak spotting?? Maybe ovulation spotting??
You'd think this was my first!!!!

Thanks in advance!!