Re: Salty milk
The milk from the less-used breast is salty and yellow because of a process called mammary involution. When milk removal is slowing to a stop, you get a decline in water and lactose (milk sugar) concentration- which means that the milk will taste more salty and less sweet- and an increase in protein concentration, particularly in lactoferrin, serum albumin, and immunoglobulins. The proteins happen to be hugely important for immune support- so this process is probably nature's way of ensuring that the baby/toddler gets one last, super-concentrated shot of immunities before being completely weaned.
You can reverse the involution process by pretending that you're nursing a newborn again- at least on the right. Nurse more on the right, and pump it more in between feedings, and your body will start putting more lactose and water into the milk. I'd aim for 10-12 pumping sessions per day- but that would be ideal, and you have to do what is realistically possible for you! A hand pump probably is not sufficient for the job- I would use a good electric pump. You'll get more milk in less time, and that will mean you'll be more likely to pump.
Just to reassure you on the cancer angle, a lot of babies will reject the salty involution milk because it is salty, not because it is cancer-y. Since you ended up with salty milk through a very natural, normal process of preferential one-sided feedings, I really think it unlikely that this is evidence of a problem.
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