This bike needs more power as I am not able to climb steep hills or steep dirt roads. Also I would like to pull a bike trailer like the Burley flat bed. I am not in it to go fast or to tearing down public roads but more torque. More off road capability.
Gordian9. To get more climbing power/torque you should change out your rear cassette. If you change to an 11-42T+ or or 11-46T cassette, this will make it considerably easier to climb because your pedaling will become more efficient, and your motor assist more effective. It
will not change the output of your motor, just make your human input more effective. Looks like you may have a 12-32T rear cassette, I cannot tell. If you change your cassette to 42T+ you will probably need to change out your derailleur, or at least get a derailleur hanger extension. You can further increase your climbing power by additionally changing your front chainring to a ring with less teeth. I installed a 30T chainring coupled with an 11-42T cassette (1400W/30amp mid-drive motor). My front end started popping wheelies on steep hills, I could hardly keep it on the ground. I ended up ditching the 30T chainring for a 40T. Still pulls wheelies on steep hills, but not as much. Total cost, $100? $150 if you change out the shifter too. BTW, if your motor is a threaded "screw-on" freewheel you won't be able do the above. It will only work if your hub motor is a Shimano type freewheel cassette
That change will give you more climbing power, albeit from muscle exertion, not motor power/torque. If you reduce the teeth in your front chainring you will sacrifice some top end speed on the flats
The next, more expensive, and more complicated way to get more power from your motor (and exhaust your battery quicker) is to change your motor controller to increase your controller amps (25-30-40 amps?) output. I'm taking a wild guest that your controller puts out 17-22 amps. This will probably necessitate that you change your display too. They need to be compatible. I think your motor is a Shengyi or AKM, you can check that. Read up on that and beware that too many amps, under too much of a load can overheat your motor quickly and break it or the controller. You can get configurable controllers that will monitor the heat of the controller and motor and reduce power accordingly. You can get a lot of info on that stuff here:
www.ebikes.ca. They are probably the best when it comes to rear hub cargo hauling bike configurations. They don't do, nor believe in mid-drives at all. You should read a lot about this and get advice before you DIY.
Take a look at their front wheel hub motors that you could add. You'd need more battery, and another controller, but their Cycle Analyst display can operate with two motors and two controllers.
If you pump extra amps into your motor(s), you will run your battery down quicker so you will need to upgrade your battery to more than your current 14Ah battery, or carry a secondary battery with you in a backpack, rear/front rack, or cargo wagon. I run with two 20Ah batteries on my mid-drive and I never run out of juice.
Don't go for "cheap" on the controller/display configuration. The Grin Technologies stuff will cost you $500-$575? to add a controller and display. A battery from Walkie is $430. So figure an easy $1,000, after you change out your transmission.
You might ask, what about changing the motor? There are rear motors with more torque, but they will need more power/amps too so you would need a new controller, display, and extra battery. I would just start with upgrading your controller first.
Lastly, if you intend to climb hills and tow a trailer, and this current bike does not work for you, I recommend that you take your first loss now. Sell your current ride and get a mid-drive bike with considerably more power after doing a good amount of research.
My Dad used to always tell me "your first loss, is your best loss".