Lubrication would help i'm sure
Some people say that tapers are bad, because they force the stretch and you can stretch further than your ear actually wants to go. Particularly if you have a "bad" taper, this might be the cause of your problems. I also wouldn't advise vaseline, as it's kinda greasy and isn't really a lubricant.
Unless your jewellery is poor quality and has sharp edges, the fact that it's a tunnel shouldn't upset anything.
See, that's bad. You shouldn't have to force it through a little at a time. If it goes, it should just go straight away with little resistance.
Whenever I've stretched up, they've literally just slid through without resistance.
You're simply not leaving enough time between stretches.
... And use a better lube, like vitamin e oil, not cream or petroleum jelly. It's really cheap. Just give it a go.
i'd love to get a lip piercing, either snake bites or half a snake bite (so just one side lol) but parents wouldnt allow it and school sure as hell wouldnt allow it... maybe something to try at uni