Sorry to hear it. My first test didn't go as well as planned either; my timing got way off after I got stuck on a hard math question.
Timing is definitely important. Make sure you know the math formulas, grammar rules, etc., and how to apply them. Knowing your fundamentals so you can quickly recall them is really key. Also work on timing strategies, like process of elimination. I used Cracking the GMAT
book) for strategy and found the tips very helpful when I got stuck.
And keep taking practice tests, but be sure to review your answers carefully. If you're getting questions right untimed but wrong on the timed tests, then continue to work on GMAT-specific skills especially.