Well that all depends. Some people are heavier wetters, others sleep deeper and longer.
Some diapers can handle side wetting, I know my CVS fitted briefs can handle one if I don't flood. Which reminds me I gotta do a write up about those sometime.... My suggestion is to experiment, and check your diapers. Some of them might got good leg guards, or even some side padding built into them.
I just hope you're a light wetter.
The breathable sides should not be letting light fluids out. It should allow some air to pass (meaning odors can pass as well), but the materials fine weave should not allow (light) liquids to pass through. None of the store or insurance brands fair too well with side wetting, even if plastic backed. If you can, invest in a good ABDL or premium brand.