There's a lot of threads on lifting and strength training programs.
I'm a 5'8" 135# make and rarely get into a situation that I can't make work. With that said don't be too big to ask for help. You only have one back and back injuries suck. I'm 24 years old and my days in EMS are numbered due to multiple cervical and thoracic injuries, none occurred on the job but the concept is the same.
Lifting is more about technique than pure power. Proper lifting mechanics go a long way.
I also two point the load-lift into the rig when at all possible or let my big macho partner or a FFer single it if they feel like risking their back.
What are you doing with these 10 pound dumbbells lift wise? The big things in EMS are leg, core and back strength. Without a strong core you can't transfer any of the power your legs generate. You can have the biggest legs in the works but you're only going to be able to lift what your core will support.
Dead lifts, cleans, squats, snatch squats, all good exercises but don't just go to the gym and pick up weights and get after it. If you've never learned to lift safely and correctly you're putting yourself at a massive risk for a permanent, debilitating injury. I know it sucks to spend money cause they're not cheap but one or two sessions with a trainer are key to learn in proper technique and get a plan that you can follow and build on. Proper diet is important as well to both physical and mental health and strength.