You're getting some bad advice in this thread from people in other states.
First, if you used the standard TREC contract, you do not have to agree to a delay. The TREC 3rd party financing addendum should specify a date by which they should have approval of their financing. If you're past that date, then they cannot terminate without penalty.
Second, your agent can give you advice, but yours sounds like someone who's waaay too milquetoast for this industry. The whole "you getting a bad reputation" thing, really means "I'm afraid the other realtors won't like me." Tough. His/her job is to represent you as the seller.
I'm in Fort Worth, so I don't know the Lubbock market. If it's a seller's market like ours here, then there's another buyer right around the corner.
I've trained my agent properly. When we first started working together, I told her, "I used to work for a mortgage company. I know that most lenders are basically lazy. They work on big-company bureaucratic timelines, not hustling-hard, get-it-done timelines like we do. They'll blame TRID, they'll blame FHA or VA, they'll tell you all kinds of things about why the deal is running late. Mostly, it's because they let things sit too long and then are making an excuse so they don't have to tell you they dropped the ball. Your job as my realtor is to tell the buyer "my seller will accept your offer, but he's kind of a hardass, so you need to stay on top of your lender."
When they come to me later and say they need a delay, I tell them all the same thing. I'll agree to one extension, of no more than a week. After that, I'll cancel the contract and keep the earnest money.
She thought I was unreasonable. She argued with me like your realtor is arguing with you. I told her to do it my way. She reluctantly did. I don't mind being the bad guy. I'm really pretty nice, but I didn't get where I am by always deferring to what everyone else wants.
Somewhere around 100 sales later with this agent, she now understands. Magically, when the buyer hears that I'll keep their EM and they'll have to start all over again on finding a house, they climb their lender's frame, and the deal gets done. I've only had to follow thru on canceling the contract a couple of times. But I will absolutely do it when I have to. It's worth losing a deal occasionally to set a precedent. (Of course, that depends on your not being desperate for the cash from the sale.)
I have no idea whether that strategy works in Maryland or Tennesee or anyplace else you're getting advice from, but it works in Texas.
Good luck.