Mummy sounds very similar to me, i am also always 28 days but last month i was a whole 12 days late, drove me mad and i didnt think i was stresssed, well not until i was late!
I tend to start BDing as soon as AF has left me so will start tonight, and then we just BD every other night and then when i get a positive OPK we'll BD on both those days, and once more after that. Then we have a rest! But we still BD in the 2ww if we want to. Hope this helps xxx