breasts feel heavy like they're full... 6 days before AF due...

Hi.

It's been in a while since I've been in here, anywhere, really, on BB, so please excuse me if I have not put this in the right place (and mods, please move it if need be).

background: I have an 8 year old and a 4 year old. My DH and I are NOT trying for #3.

Anyway.
I'm on CD 23, 6 days before AF is due.
Yesterday and the day before I've been feeling like my breasts are sore and heavy, like baby is due for a breastfeed.
Yesterday, I squeezed one breast and there is the tiiiiiinest amount of clear colostrum type stuff that came out.
Today, one (the right one) is really heavy and is busting out of my bra cup. Still sore and heavy as noted above.

Any suggestions? I've been to the doctor (about various other things) three time this week, and I really am not in a hurry to go back about this, which may just be nothing...