Flakey Seller - Should I be worried?

[Carl Montgomery]

I'm buying my first home and getting super stressed with the experience so far. The house I'm trying to close on has been on the market for five months (sellers market, right now houses are typically disappearing a few days after going up for sale). I thought the seller would be jumping out of his seat to get a purchase agreement in place, but my agent seems to have a hard time getting responses from the seller's agent. They've not responded to my latest offer and it is past the expiry date/time. My agent asked the seller's agent whether they planned to respond. One word reply over text "Yes". So fast forward hours later, my agent has to call to try to get more information. The seller's agent says that they don't like the closing date and insist on moving it 15 days ahead (side note, I am offering them the same terms as one of their previous counter offers, and there isn't even anyone living in the house right now. Why change that now?). But fine, I can settle for the closing date that the buyer wants. So of course we should be getting their rejection email any time now right? Nope, still waiting several days after that last counter offer I made. The house seems to have been for sale for a long time considering the market right now, and we're offering what the buyer wants. What do you think?