Re: New kit...parents say no.
a couple thoughts from another older drummer who knows what it's like to be a parent but also remembers what it's like to be in your shoes...
As Dogbreath (et al) said - PATIENCE is a good thing. you have to ask yourself - do you NEED this new kit? It sounds more like this is something you've convinced yourself that you really WANT. There's a big difference between the two and knowing the difference will help you stay sane. The thing is - if you wait, you may desire something else entirely different in another 18 months. Desires have a way of evolving over time as you change. You don't want to find yourself 1 or 2 years from now wishing that you didn't have that small kit because you just got a gig that requires a different (big kit) sound. As others have wisely pointed out - you have a nice kit already and this could be good opportunity for you to play around with different setups and tuning until you have figured out how to get everything possible out of the Tama's.
Also - by waiting, you can keep your eyes and ears open to see if a really fantastic deal pops up on the drums you want. Six months from now (or whenever), you might run across somebody who has the kit you're looking for and because of exigent circumstances, needs to get rid of it in a hurry and you could end up getting a great deal on it. There's a lot of value to knowing exactly what you want, but having the patience to wait for it. I suspect your parents might be more open to it if you can show them what a deal you've found (and they know you've been waiting patiently).
I know a lot of musician's (especially guitar players - for some reason) who are constantly trading and swapping intruments. There's nothing wrong with treating your drums as a commodity that can be sold or traded to get something different. If you're a sharp trader and are able to acquire things for a little bit less than they're worth and then get more out of them when you get rid of them - you may find that to be a good potential source of income... but the only way to make that work is to maintain emotional detachment and not let yourself be overly influenced by your desires.
For what it's worth - when I was your age, my drums and cymbals got handed down from my older brother (who was playing semi-professionally before he got out of high school). So while I had decent drums, I never had a kit that I was able to pick out for myself (it drove me kind of crazy, but I still played the hell out of those drums). Anyway - I got away from playing a few years after I graduated from college (life changes: marriage, family, career, etc.) until three years ago when I realized that I just HAD to pick it back up. My old drums were still stored in the basement of my parents house, so I dug them out, cleaned them up, tuned them up and played them one time at a jam session and decided that NOW was the time to get some new drums. So at the ripe old age of 45, I finally bought the first drumset that was exactly what I wanted (Tama Starclassic 5 pc bop kit). They weren't even brand new - although they were in virtually 'like-new' condition. Still - it was so sweet finally having my dream kit - and I appreciate those drums so much more now because of all the time that I waited to get them. I'm not suggesting you should wait 30 years to get new drums - but in context, waiting 1 or 2 years isn't so bad.
Lastly - you're at an age when listening to your parents may just get to be harder and harder. you probably want to establish your own sense of independence and listening to them (especially if they're being a little bit, or a lot, irrational) can be hard to swallow. Convincing them of their irrationality might be impossible - so at some point you have to decide what is more important to you - getting what you want (in this case a new kit), or maintaining peace at home. There's nothing wrong with knowing what you want and going for it as long as you know what the consequences of your actions will be and are willing and able to deal with them. Taking risks and maybe even making mistakes will teach you a lot but your parents may have a hard time letting go enough to let you experience that, or maybe they're just trying to keep control of you for as long as they can (I don't know them, so it would be foolish for me to guess).
just my humble opinion - sorry for rambling on and on...