and I also agree with Dee and Antonialisa. Other people don't get to decide for us what is "enough." Now, I have considered that the many options now for fertility treatment may make it harder for people to stop trying: we think it's somehow in our control, whereas in the past it might have been easier to grieve and move on. But given that we DO have those options, I think each person/couple knows in their heart how far to go. Sometimes it's also a matter of taking a break for a while before trying again or moving to a different stage (like DE or surrogacy).
As for your mother, I would thank her for her input (nicely if you can), but listen to your own heart. I wish you peace, whatever your outcome.