Hi Eliana: I understand what you are describing. It can be a big adjustment going to the next five pound increment. The type of dumb bell you are using can also make a difference in grip. I prefer football handle grips and feel they are much more secure in my hands.
It may be helpful to use magnetic weights with the dumb bells. I've provided a link to some from Perform Better. But there are other versions of these elsewhere if you shop around.
http://www.performbetter.com/detail....tegoryID_E_351
I also agree that there is a point where the goal for the next sized dumb bell is not a priority. If you have found a range of strength that has made you satisfied then look into other ways of training that muscle group. I would suggest adding flat bands into your training. It just adds another dimension and keeps the workouts interesting.
http://www.resistancebandtraining.com/
And yes, doing a pushup with these bands is sadistic fun.

May I suggest the monster black mini...
You have the correct idea of changing reps and set schemes. Also consider changing the rotation of your workouts. Make sure that you are not always placing maybe the chest press first or the pullup first. Try working the chest in another way like maybe cable fly, followed by a lat exercise then add the chest press...those dumb bells are going to feel a whole lot more challenging if they are introduced in a new place of your workout.
Just a thought.