If I couldn't afford to keep paying my lawyer and don't know if he is going to appear at court in 3 days, can I still be sentenced without counsel being present?

Your lawyer remains the attorney of record and is required to appear in court until the judge relieves him.  That being said, just because the case is close to being over you are also required to maintain your side of teh contract.  Your attorney has lived up to his end of the bargain by working out a plea bargain that was acceptable to you, you should live up to your end of the contract and find a way to pay for the services as promised. 

Your lawyer must appear in court at the upcoming hearing despite your inability to pay him or her unless the attorney has received an order from the court allowing him or her to withdraw as your attorney of record. If he or she does not show, you could be sentenced by the court for your conviction.