Welcome! It was a good idea to post in 2 places, so don't worry about that. :)
First of all, some reassurance: If the baby is generally happy, healthy, and growing, I would not be overly concerned. It can be really hard to separate out allergy/intolerance from OALD/oversupply, so it may take some time to get this figured out. But with a happy, healthy baby, you have the time, YKWIM?
How bloody are your baby's poops- is it just streaks/spots or are you ever seeing more substantial amounts of blood? And is the blood bright red, or is it brownish/blackish, as if it has been digested?
Do you see any additional OS/OALD symptoms, like fast letdowns, rapid feedings, baby pulling off the breast during letdowns, milk squirting/streaming from the breast when baby pulls off? And let's say you were to pump- how much milk do you think you could get? (Pumping is not a reliable gauge of how much milk you have, but if you could get a large amount of milk pretty quickly that would help point towards OS/OALD.)
If the culprit is dairy and soy... Then maybe? It depends how thoroughly you've cut them out and how sensitive your baby's response to them is.
-Should I be seeing improvements (even minor ones) from cutting out dairy and soy?
Again, it depends. In my experience, treating oversupply is a 2 steps forward, 1 step back process. I'd think I was making progress, only to see a whole bunch of green, mucus-y stools and blood streaks all over again. Frustrating!
-Should I be seeing improvements from block-feeding and correcting oald?
Another "it depends." Is the cause an allergy/intolerance? Are you eliminating the right things? How sensitive is the baby? How complete is the elimination? etc.
-Can a slip up in diet cause consistent green mucous stools with the occasional bloody stool for this long?
I have yet to find anything suggesting that consistently green stools in a happy, healthy, growing baby are an indication of "low nutrient" breastmilk. Breastmilk is actually remarkably consistent in composition from mom to mom, and even poorly-nourished women create good milk. So I wouldn't worry about your diet. Remember, it's totally normal to lose weight while nursing- that's why we gain weight during pregnancy and generally carry more fat than other mammals.
-Can baby have these symptoms from not getting enough fat or nutrients in the breastmilk? Should I be eating more fatty things? (I’ve been adding canola and olive oil to stuff, eating avocados, peanut butter, fries (thank you chick fil a!), potato chips, nuts but can’t seem to consume as much fat as I did on dairy/soy). With my first I ate and ate and ate and still lost more weight than I gained while pregnant. I'm worried this baby isn't getting enough fat in my milk since i've cut out so much.
It would not hurt to cut out beef. And watch out for what things are fried in- like those Chik-fil-A fries- they could be fried in beef tallow... I think Burger King's used to be until they realized just how many devout Hindus were appalled by what they had consumed...
-Should I try eliminating more things from my diet like beef? Would an elimination diet be the next logical step?
And as for the elimination diet- I'm not sure it's the next logical step, but again, it's not something that would hurt to try.
I have a friend whose kid is very dairy-sensitive, and she swears by a daily probiotic as the thing that allows her little girl to eat limited quantities of dairy.
-Has anyone seen improvements by using a probiotic and if so what kind is safe?
Yes, a LC could definitely help out, particularly with figuring out if this is more suggestive of an allergy/intolerance or OS/OALD. I suggest going to see one who is an IBCLC- they tend to have the best training.
-And lastly, could a Lactation Consultant help me with these issues? (pedi isn’t too helpful)