Your arms get tired because your not using your wrists to do the work. Check out the "Moller Method".
YouTube - the moller method
Another thing is that rudiments are very important to master. Practice them at least for warm ups.
Your timing and tempo are good. Try playing to music, along with a song.
I know it's hard with today's economy to afford a good drumming teacher. But as the President says, "Do More With Less.
Overall, not bad for a beginner at all. Remember that practice makes perfect.
Good luck on your venture and Happy Drumming.