"But that doesn't mean we neglect our parent's feelings and opinions." There are two people in a relationship/marriage and your mom and his mom are not either of them. You need to learn WHICH decisions moms get to weigh in on and which ones they don't.
There are times you and your partner will make a decision without any input from anyone and then you just announce your decision. Your relationship is not a family democracy, and if you treat it like one, your relationship is likely to fail. Appropriate boundaries with extended family is very, very important. It's concerning to me that your bf won't tell his mom to butt-out. What's it going to be like when she wants a say in how the kids are raised?
There are lots of potential solutions here about when/where to move (or not). But the point is that the decision is yours, not your mom's and not his mom's. You already know their opinions so tell them the subject is now off-limits and you will make an announcement if/when there is anything to announce.
You're 30 years old, not 17. Part of adulthood is making the best decision you can even if mummy gets mad or sad or throws a tantrum. It's no longer her job to cater to your self-esteem and it's no longer your job to do what she says. Fun times.
ETA: There is an easier way but you refuse to do it that way. And by the way, if making a decision that your mom disagrees with somehow ruins your relationship, it's not a very good relationship. It's a controlling and manipulative one. If your relationship is healthy, there is absolutely ZERO reason that your mom needs to be happy about all your decisions.
I do not mean this to be snarky, but you really do not sound like you're mature enough to be in your 30s, nor do you sound mature enough for a commitment like marriage.