SP is top of your pubic bone, hmmm, easy not technical way to feel for it, feel your vag and then feel up to where you feel the bone end... thats the top...

Your fundal is the uterus so from the SP feel your belly *do laying down* to where the belly kinda drops off your feel a large mass thats the uterus... HTH

Being that your 34weeks, fundal height should be around the same, and should be about 14cms from your belly button to top to fundus, but that is only a guesstimation.