Bacon can easily be made without nitrites, without fear of botulism. Whole muscle cuts (such as pancetta, bacon, etc) do not require nitrite/nitrate rich curing salts for microbial protection, but instead are used for the characteristic ham/bacon colour and flavour. C. Botulinum can exist on the outside of whole cuts of meat, however this is an oxygen rich environment. For CB to grow and produce the fatal toxin, they need an anaerobic environment. If you cure whole cuts, that environment isn't available and botulism is not a risk. Once you grind the meat for salami or dry cured sausage, however, those CB bacteria are then transferred to the inside of the sausage to an anaerobic environment and there can be some chance of botulism poisoning.
I use nitrites most of the time, but I can certainly understand why you would want to try avoiding them given your migraine situation.
Making bacon is a fairly simple process, which can be done without a smoker, still with good results.
The basic starting point is the dry cure - generally salt (around 2-2.5% weight of pork, depending how salty you like your bacon), pepper and sugar. You can use different types of pepper (mountain pepper berry, black pepper, green pepper, white pepper) and sugar (white, brown, honey, maple syrup) to vary the flavours. You can also add aromatics (garlic, bay, thyme, paprika, liquid smoke) to add a depth of flavour.
I cure in a ziplock bag to prevent mess. Rub the dry cure into the pork belly all over and stick this in a zip lock bag for around a week to 10 days in the fridge. Due to the fact that you're using a specific amount of salt (based on the weight of the meat), there's no issue with over-curing, so it's better to err on the side of caution and go 10 days, but it may be ready in less, dependant on the size of the belly. During the course of the curing process, liquid will be drawn from the belly and the meat will start to harden up. If you remember, try flipping the belly over each day, and you can even massage it to ensure that the cure works its way into the muscle fibres.
Once you've cured the belly, remove it from the ziplock bag and rinse the cure off. You don't need to get it totally washed off, just rinse it to get the majority off. Some of the cure can still remain to add a bit of flavour on the outside. Once this has been done, pat dry with paper towels, then put the belly on a wire rack and pop it back in the fridge to dry out a little. If you're planning on smoking it, you want the belly to form a pellicle, which is a sticky layer on the outside of the meat. This gives the smoke flavour something to adhere to, however if you're not smoking the belly, just lkeave it long enough for the belly to be pretty dry.
At this point, you have bacon that you can slice and fry, however you might want to cook your bacon. Keep your bacon on a wire rack and put it in the oven. Turn the oven to 100*C/210*F and leave it in there for around 1.5-2 hours, depending again on how thick your belly is. You want to cook it to an internal temperature of 68*C/154*F. During the process, you can glaze it with something sweet like maple syrup, but it will still be delicious without.
After you've cooked it, let it cool and then slice it. It's easier to slice once it's been cooked in the oven, and easier still if you get it really cold before slicing (i.e. almost freezing!). You can pack slices into freezer bags and freeze it.
I have a post on my blog about it which goes into a bit more detail.
Really, with a nice cure and possibly a bit of liquid smoke (if you want), you could make a great bacon that would taste wayyyy better than anything that you buy in the shop. No need for nitrites or nitrates.