Soldier on and hope for the best. Enough of your bacteria may have survived to make it all right. Temperature control is problematic, and more so for smaller batches. I make four gallon batches and they are easier to keep a steady temperature than the two gallon batches that I used to make.
There are a couple of other ways to heat the curd. The first is to work with your pot in a sink or large basin full of hot water, and add hot or cold water as needed, so you just keep a kettle on the hob and add some boiling water to raise the temperature.
Another technique is to scoop out some of the whey and heat it, adding it back to the curd in small amounts to raise the temperature gradually. The woman who got me started in cheese making does it this way, and she does not use a thermometer. She stirs the curd with her hand, starting at "blood warm" and slowly raising it to "fever warm".
