You and your colleague are not working well together, you’re very different. You like to think things through, the other is criticizing you for being too slow. You argue a lot and get in each other’s way. Why don’t you both sit down and first get off your chest what bothers you, speak candidly and listen attentively? Then speak about the strengths you admire each other for. See the potential to join forces and work as partners. Your differences will remain. But don’t let them drive you apart. When you agree how to complement each other you’ll be stronger together!
You’re under pressure because you definitely started this important project too late. How