Unfortunately the ultimate responsibility will be yours, you signed the agreement,. Your lawyer is there to protect you and should of been aware of the dates, and either asked for an extention or informed the sellers you could not obtain the financing. Your buyers agent could also be accountable if it is demonstrated that they took the responsibility of being the contact person for your lender.
Either way it will be a long drawn out costly mess. Best advice is to explain it to the Seller, see if you can get the financing, if not, see if the seller will be a generous person and help you out. (not likely as they have had the property off the market and may not be able to sell it or get the price you have offered.)