Sounds like you were off to a good start, J.. Good for you for deciding to breastfeed! You'll never regret it!
He may be going thru a growth spurt or getting sick. I'm not really understanding why you introduced the bottle since you're home with him, unless you were thinking you'd need to leave him sometimes??
It's great that you still have a good milk supply. One important thing is to be sure his weight isn't suffering as you transition back to complete breastfeeding. Your 1st priority is to be sure he's getting enough milk and growing. Some kids don't do well going from one to the other even if they seem to be OK with it for awhile. I would keep working to get him totally back to the breast for many reasons. Catch him when he's sleepy, perhaps hand-express a bit of milk to soften your breast if it's very full and let him taste it a bit before trying to latch him on (put a few drops on his lips). Try to empty one breast at each nursing so he gets the rich, hind milk and so you won't risk mastitis. Try putting him to the breast more often. If you're engorged, you can put a cabbage leaf in your bra between feedings.
I'd suggest you consider coming to a La Leche League meeting and getting support/advice from other moms. You can go on the website to find a local group www.llli.org. A lot of the groups meet the first week of the month. The Warren group meets next Monday morning, for example, and the Ferndale/Oak Park daytime group meets next Thursday morning. Also, there's a lot of info on the website. Click on Resources, then onto the section that has Answers.
I'm sure you can work this out at this young age, but it may take a little doing and a lot of patience. I sure wouldn't give up! You can also try giving him breastmilk with a cup, a spoon, or a medicine doser as you work to eliminate artificial nipples, and I'd try not to use a pacifier which is so similar to a bottle nipple. Artificial nipples are easier for them to suck on so sometimes they stop wanting to work at getting milk from the breast. I'm sure you can "woo" him back to the breast totally. Hang in there! Obviously you are a very loving mom. You'll make it! Perhaps you can use a bottle occasionally if you need to go out, but it sounds like this isn't the time for it. If you can wait till he's on solids, it will be easier to leave him without these issues. A lot of breastfed babies never use a bottle at all.