While baby is important, your own wellbeing, mental health and sanity is equally as important. Don’t give yourself too much pressure on having to bf and you’re doing a good job to even try already. Moreover, most babies starts solids at 6m and will get their nutrition from solids/formula as well.
Baby’s poo issue can consider giving probiotics (I gave Lactogg/biogaia). I cannot advise you on the diabetes part as I’m not sure how that works too but I didn’t really control my own diet during bf and my baby is fine (she’s 3yo now), but of course, everything in moderation. I ate too much spicy food and had many episodes of mastitis 🥲.
As you’re still bf, it’s still better to limit the intake of spicy/oily/sweet stuffs as it can contribute to block milk ducts easily and may lead to mastitis, but normal intake is fine, maybe not everyday (especially spicy food).