Going to try and voice my thoughts on surrogacy, might be rambley, bear with

Firstly, I am completely against 'renting' a womb of a woman (especially a wealthy couple using a surrogate in a poor country). What really peaked me was when Kim Kardashian used a surrogate for her later pregnancies, it felt icky at the time but I wasn't sure why. I know it's sad when woman can't carry children or gay couples can't have biological children, but sadly that's life and life's not fair

a woman's body is NOT for rent, it's not just an incubator where the baby grows and then pops out with no attachment to the woman who grew it. And it's so wrong that a human can BUY another human to grow their offspring. To me that's on a par to slavery.
Where it gets murky to me is a family member offers to help out. I don't know if my sister was struggling with infertility, would I offer as I love her more than anything? But that opens a whole new can of worms. What happens if after growing the baby for 9 months I don't want to hand them over and decide to keep it (as I'm sure is allowed in UK law). What happens if the baby is disabled and my sister turned around and said she didn't want it? What if something happened to me? Could my sister live with the guilt? I know I couldn't if it was the other way round. And all those situations are based on me offering purely out of love. What about if I was very poor, struggling to pay rent or put food on the table, and my sister was very wealthy and would pay my expenses for 9 months for me, that surely changes everything and by having surrogacy legal it opens up poor women to being exploited, even if it's by their family.
Not sure if any of this makes sense.