Partner (33F) and I (24F), together almost 3 years. We're talking marriage, but my parents (50's) still politely refuse to meet her.

I'm seeking some advice about navigating a complex family dynamic while trying to understand my own wants and desires.
Sam (alias) and I are happy. My family is happy. But my family has no desire to meet or interact with Sam, and Sam is no stranger to familial neglect. As she only maintains a relationship with her sister who lives out of state, she is content with our urban, ***** nuclear family (two moms, a pupper and cat.)
I could get into Sam's family history (and type furiously) but suffice it to say, she is a success story in SPITE of her mother and extended family. Naturally, she's not keen on "family" and had a lot of hesitation surrounding marriage in the first place. We've been seeing a couple's therapist to set up our relationship with a strong foundation and work out any issues before the big C. (Commiiiitment)
I had the opposite experience growing up. Had it not been for my family's attention and care, I would not be half the woman I am today. The reason I am able to communicate with you all is because of the sacrifices my parents made to ensure we moved to a country with better economic opportunities. We're immigrants from a small latin country-- family is everything.
Of course there's tension because I'm queerful, but it's been 6 years since the other big C (cooming oouut) and my parents have grown more tolerant. My partner never comes up in conversation nor do they inquire about my personal life. They know of her, know we bought a house and raised a dog (they love the dog) but they're always side stepping calling her my SO. Occasionally, my mother humors me when I talk about her, but she's not enthused. It may not be the right time, but I at least have been pushing for Sam to join the family for Christmas. No promises were made, just hand wavy maybes.
Sam would like to be included, in the sort of way someone entertains fanciful fantasies. She wants to impress my family, hang out with my sisters (they have come to the house once before. They're supportive.) However, she is fine waiting until they're more receptive.
Am I pushing too much? Am I not pushing enough? Is there a timeline with these things, or an order of operations? I don't want to put wedding plans on hold because my family hasn't exactly gotten to know the bride yet. Sam isn't crazy about weddings anyway.
The big kicker is telling my parents about getting hitched. The even bigger kicker is having to tell my Dad we're doing a post-nup (like a pre-nup, but after the wedding.) Can't avoid that one since I'm going to need his access to a lawyer.
How do I work up the courage to ask for respect and inclusion?
Thanks so much in advance.
TL;DR You don't have to be gay to understand how upsetting it can be to know your relationship will never be celebrated by your parents.


Source.