While being in blockstun, you'll still be blocking even if you're not holding back (until you leave blockstun). This is called absolute blocking (although I heard 3rd strike doesn't have it due to the threat of red parry).
Also keep in mind that 1 is a position for blocking as well, just crouching blocking (which won't block overheads), as opposed to standing blocking (which is vulnerable to lows).
Switching to octagon might make the input itself feel different when you do it, but it won't help you block better (although optimally you're not "riding the gate" and just doing the motion without hitting the outside edge).