Re: to cross train or not to cross train?
I think the best thing you could do for yourself, your Aikido, and the Aikido community as a whole is to study a few other martial arts. Only one you step outside of Aikido, can you really appreciate certain aspects of it. A physical martial art is a good choice. I would also suggest finding something that has heavy sparring practice. Like Judo, Jiu Jitsu, Kickboxing or western boxing. It's interesting to start playing with people actively working against you in a constructive way.
Be open to what you are doing, you could decide you like whatever martial art you try better than Aikido. You could see Aikido anew and have an even deeper love for Aikido. Be open, it can only help!
I was around your age when I started doing competitive Jiujitsu, it was the best choice I ever made. It also made me appreciate Aikido more than I ever had before. If you ask me, GO FOR IT.