Congratulations on sticking with breast-feeding! It's a common reaction for baby to dislike rice. Have you tried it? It's disgusting. That's why I started my babies on apples. There are lots of theories on whether you should start cereals first (to make sure there aren't allergies) or veggies (so they don't reject them after fruit) or fruits (so they will enjoy solids). I can tell you right now, there is not a reason why a baby needs cereal first. As long as you introduce ONE food at a time, you will know that they aren't allergic. I made most of my babies' food, so I would cut the apples up and boil them to soft and then puree them, then you can strain to make sure they're almost liquid form. I would NOT do it through the bottle. If he's hungry, let him nurse more. Breast milk has protein, fat, water, and everything else they need at this age. Some babies are ready for solids by 5 months, but if they need to drink it, they really need to drink breast milk or formula. How often is he nursing? Babies at that age should still be nursing 7-8 times per day. If he's sleeping through the night, that means he needs to nurse every 2 hours between 7 am and 7 pm (for example) - 7 am, 9 am, 11 am, etc until 7 pm. IS he really nursing more than that? If that's what he's currently doing, it sounds like you're doing it right. And, don't worry, soon enough (between 6-8 months) he'll be nursing left and you'll miss those times you had to hold him and cuddle him without him crawling off to discover new things.
I also found this really interesting article that might help you decide what to do: http://kellymom.com/nutrition/solids/solids-when.html
When he is ready for solids, start solids with a spoon. Most of it does get pushed out while they learn what to do with their tongues at the young age. Starting solids is mainly to let them practice tongue thrust, etc and to experience different tastes/textures. Even your doctor wouldn't expect additional solids to add many calories to his diet. Around 9 months is when they really start replacing breast milk feedings with solid feedings.