I had a very personal experience with just this kind of situation, and it ended with my company folding. Here are some tips to make sure the same thing doesn't happen to you:
1) Fail fast. This is ALWAYS rule #1 in a startup. If there are any terms and conditions required for the offer to go through, make sure you understand them and make sure the conditions can be met. Will any of you need to relo? How many of you must be retained and for how long? Are there any "proof points" required for the purchase to go through? It may seem strange, but your goal is to get them to reject you by pushing on any weak parts of the deal.
2) You haven't finished until the check CLEARS. Never, under any circumstances, assume that things will go well. In my experience, we were assured several times by high-ranking members of the acquiring company that everything was great and we had nothing to worry about. Don't believe them. It's business, and if business conditions change before the check clears, you can be sure there's some kind of escape clause in the contract. So, until you've taken the money out of the bank in large denomination bills, the deal isn't over.
3) Forget about your feelings and do what's best for your young business. This can be REALLY hard. It sounds like you're in a similar situation to the one I was in: the large company offers scale and ability to execute that you will spend years building. Your company seems to be so young that there is a lot of risk and uncertainty. But, is your young company experiencing traction? What would the impact be to your business if you are distracted for 2-3 months working through terms and have nothing to show for that time? Have you made it to the point where people understand the value you will bring? In other words, would they miss you if you disappeared? If so, your company may be better served by building those relationships with your current or future customers and generating some "raving fans".
HTH