Welcome to the forums! Great to see some fellow teens be serious about umpiring. I started at 14, as it sounds you did, and I wish I'd found this resource as soon as you...
I'm in the same boat as @BlueRanger, doing 9u to 14Um, and would give pretty similar advice to the others here. Don't cheap out, and have gear ready to take you to the next level. If you think about it, getting quality equipment really isn't that expensive (think of it in game fees), but will have a huge effect on how long the gear lasts you, the protection you get from the gear, and your comfort.
For CP, I have the Champion, and it does a great job. I think the others here have said enough about it, so I'll just say I concur with them.
For Shins, I splurged and got the force 3's. I'm not going to say I necessarily recommend them, but only because they're total overkill for what you'll be doing in the near future, and they're expensive. That being said, I can't see myself getting a new set of shinguards anytime in the foreseeable future. You feel nothing when you take a shot, and they're super comfortable. They're pricey, but they're the best. Sounds like they may not be the choice for you, but I'd keep them in mind if you ever decide you want an upgrade.
The piece of gear I've picked up that has surprised me enough has been an odd one. It's my socks! I was shocked at how much of a difference it made for me. I picked up a pair of the force 3 socks off of ump attire (pretty sure it was to get me into the free shipping range), and I'm super happy I did. Doesn't have to be those, but a few nice pairs of thick, but breathable, calf length or higher socks would be a great investment.