I think you need to stop development. Don't put another minute into dev work until you've found someone to pay for this.
Sometimes it's helpful and motivating to approach the first few sales in a completely non sustainable way. Don't try to establish a customer acquisition funnel - try to find one single person willing to pay.
It sounds like your December 31 users are a good place to start. Send each one of them an email and give them an incentive to renew before the accounts expire. Offer them a discount or something for every referral they bring in for a trial or as a new customer or a discount that is a bit higher for every trial day they have left so people feel an urgency to move on it now. Try to convert ONE trial customer into a paid customer over the next three or four weeks. If you fail, it's not your software, it's your sales and marketing skills. Take that as a hint that you might need to bring in a new person to do that for you.
It sounds like you're quite adept at building product but it's not a business yet. It's time to stop building and learn to convince people to part with their money. Building a better tool isn't enough. You have to build a better tool, educate them on why its worth it, eliminate their reasons not to buy, and then ask them to take action.
I recommend taking a break and then consider bringing in some outside expertise. Someone who knows how to sell online.
Nobody builds an empire alone. It just can't be done.