Is the pension plan inflation adjusted? If not (which is my guess) and inflation is 2%, the pension will only be worth 74% of current buying power in 15 years, 41% in 45 years. This could leave you in a bind in old age. Also, what will happen if one of you dies? Your wife could be in real trouble living off only her pension if you wind down your nest egg. I would advise using the pension as a back up plan and save the full $600,000 (you're not far off).
On a side note, I would be upfront with your daughter about how college will be paid for, which means you should decide that before she starts applying.
Once your daughter leaves, you might also be able to reduce your spending (smaller condo, fewer groceries, eating out), or you might increase it (fancy date nights, cross country flights to visit her).
Bottom line: Retirement in 2 years is doable, but it'll take some work, it sounds like you're flexible and are building safeguards in, but I'd gp for the full 4% + pension.