You sound similar to me - I was right around you were at that age. My income increased significantly in the last 5 years and I've moved into the management ranks. At 27, don't hesitate to invest in yourself if that will help (be that an MBA, advanced degree, or other means.)
As far as Mom, I'm effectively her financial advisor. She fully plans/wants to give all of this money to us, so we're doing it in a tax efficient manner (read: slowly.) Short on that, as you said, dividing it by 5 means less of a windfall, and I don't factor this in at all.
I'm hoping to be retired well in advance of any inheritance I would get.
As far as Mom, I'm effectively her financial advisor. She fully plans/wants to give all of this money to us, so we're doing it in a tax efficient manner (read: slowly.) Short on that, as you said, dividing it by 5 means less of a windfall, and I don't factor this in at all.
I'm hoping to be retired well in advance of any inheritance I would get.
I am now/will likely be in a somewhat similar position to you at your age as well.
I can't give solid advice but I have had many similar thoughts that you have had. I am 27 with a NW ($310k) and income ($85K) much lower than yours, but I suspect by 35 I will have around the same NW as you (and hopefully the same income! ). My parents are also affluent with a NW of about $5m but they live fairly frugally for their NW (only spending $100-110k/year). I spend about $4k a month max (likely less) in after tax money, so would also need about a $2m portfolio to support a 3% SWR.
I have thought my future plans countlessly over and over again given my situation. Given my current portfolio and annual savings rate, I might not reach $2m (in today's dollars) until my ate 40's, assuming my pay only increases with inflation each year. However I am confident I will be promoted and will be due for some sizable promotions which will increase my savings, but I don't factor that into my modeling.
At any rate, I basically have come up with three scenarios for me, which may apply to you too:
1) Work until I can support a 3% SWR (basically until 45-50).
2) Work until I have enough assets to withdraw 5-10% a year with the idea that I would inherit more funds later in life. Obvious there are inherent risks/tough decisions involved with this one.
3) Do #2 above, but find part time work so that I am essentially only withdrawing 3% a year.
Of course, there are pros and cons to all of the above. #1 is the least risky but #2 and #3 provide more freedom. #2 and #3 would also involve some family estate/inheritance conversations with your mom which might not be welcomed - it all depends on how close you are with your mom and what you think her plans would be for the money. The conversation may be very welcomed and well received by her. Or, it may be very unwelcome. I haven't had any inheritance talks with my folks, but I will say that they are very impressed with my disciplined savings and the fact that I haven't frivolously blown through my trust fund that they gave me. Another thing to keep in mind is that you have 5 siblings, so that $3m won't go nearly as far divided 5 or 6 ways.
#2 and #3 above also would give you freedom to spend more time with your mom in her old age (think, spending a winter in FL with her), which would be invaluable, of course, and something you could never replace.