By design, escrow accounts are never supposed to drop below a "reserve" amount. I'm not 100% certain but I believe that amount is two months of escrow payments at the appropriate amount to cover taxes and insurance. Your lender is required by law to send an escrow statement once a year, which typically happens when they recalculate your new escrow payment for the next year.
I see on your most recent account statement that your escrow balance is -$1500. That is way out of whack, if your escrow payments are typically $200-300 a month. Something isn't right there. When your mortgage was sold, was the old company sending you a check for the amount left in escrow or were they passing that on to the new company? If they were sending you a check and you cashed it without forwarding those funds to your new mortgage company that could explain why your balance is so negative. If the new company had to pay your tax bill without having funds already in the account that could make the balance that negative.
The good news is that this situation will rectify itself after one year, assuming your loan isn't sold again. Once the escrow shortage is corrected in the current year, your new escrow analysis will return to only collecting the proper amount of money needed to pay your taxes and insurance.
At that time, if you learn you have overpaid your escrow and there's a significantly higher balance than should be, they will be required to send you a check for the overage