For the first 2 wards, I personally prefer giving the wards to my mid and offlane. I trust myself to control my lane without the help of an observer ward for the first 5 minutes.For your ganking concern, communicate with your mid ahead of time. They should be able to manipulate creep equilibrium or bait the enemy out of position so that you can avoid the situation you described.For sentries, you may be spending too much on sentries. Try to use your sentries efficiently. Ward only when necessary and no more than that. Don't drop a sentry near an enemy objective unless your team actually plans on pushing towards said objective. You don't need to cover every pathway. Figure out what's crucial and what's not crucial and learn to ward only the crucial areas.For stacking camps, try to not see it as a main goal, but more of as something you do whenever you can while you're doing something else. When you're on your way to your team or to some spot you want to ward, if you notice the in-game timer nearing X:50, stack a camp near you. I hope that made sense.

P.S. If you want to really grind the enemies gears, go stalk out where the enemy support sets his mid ward or get windlace and rush to set a ward at mid high ground, then remove it with a sentry. You get the price of the sentry back instantly from an observer ward so you've lost nothing by buying it, but the enemy has lost vision to your high ground and your mid won't get harrassed nearly as much. But I'm trash mmr and mostly play unranked, but with Venge, Ogre, Necro and Rubick I have a consistent +65% winrate as pos 5 so I must be doing something right.