I had this last month in my 2WW - however i am 99.9% positive that they were tender because i was pushing them so hard and willing them to be tender and give me a 'sign'!! ha ha!
I get them before O all the way to flow. But I also got them when I was PG... but they were different, heavier and fuller right away(like a cup size fuller). I hope this is a sign for you. I'll be keeping my fingers crossed and try not to drive yourself mad.
P