Question Regarding Normal Audiograms

Hey so when I went to the audiologist I had normal hearing, 7db for freqs up to 8000hz. I still have tinnitus because of much higher frequency level loss I believe. My question is will this get worse? I'm 18 right now and I'm just curious as to how long it can take for my ears to get hearing loss, possibly in my 30's-40's I can get mild hearing loss? I take care of my ears now and don't listen to music loud or anything so I'm hoping I can prevent that...but if it's a natural thing that our ears get worse I don't know what I can control...

 

It's not going to get worse if you properly protect your ears. For example by wearing inner earphones.
Train stations are too loud, sporting events are too loud, earphones on 75% of max (or over) are too loud, high density traffic is too loud, etc. Don't go into a nightclub without spending 30 bucks on quality ear protection.
Once you hit old age your hearing might drop a little but this varies greatly between people. Be healthy and you'll probably last a very, very long time. Far beyond the point at which we're able to cure hearing loss and tinnitus.