do you have symptoms of opening up? as it sounds as though you are worrying about it as a possibility, not that anything has actually happened to cause you to believe your stitches have actually opened up....in which case don't worry, just look after the wound and keep an eye on its healing.
i wouldn't look unless you have to. feel it and see if it feels like somethings opened? if you are concerned they have actually opened up, ie genuine concern rather than just because youre worried, i think you should ask your midwife to come earlier.
i presume you're washing regularly after every loo?
sitting on it shouldn't cause it open up. but if its uncomfortable to sit on,then get a swimming ring or if you dont have one and cant send anyone out,then place some towels in a ring and sit int that. it puts less pressure on the area.
it is normal for the stiching to jut out to one side, a common episiotomy cut is to the right as this helps avoid damadge to the rectum.
also try salt baths and regular airing (sit on bed, legs open, no undies and an old towel under you to catch your bleeding).
oh and if in a couple of days its gets really uncomfortble (usually around day 10 it feels like burning,prepare yourself for that,its the skin tightening and the stitches falling out as they should) femipads or cool gel pads work wonders.