So I'm a skinny guy & wondering if I can gain some weight in my situation...

I'm 16, 5'11 & weigh about 120, & as a baby I was diagnosed with PKU. My mother never really gave me different kinds of foods that other parents would do to their kids because she was afraid I'd be retarded. Year after year she'd take me to a doctor to see how I'm doing and in October was my last recent visit. He said that I'm fine and that I really don't have PKU, he also mentioned that my weight is fine for my age and eventually my weight will catch up, also that I wouldn't be a great body builder since I couldn't receive much protein. So my problem is that I can't get myself to eat regular foods like other kids my age. I basically eat the same foods everyday. So my question is reddit, how can I convince myself to stop being a wimp and taste other foods? For some reason I just can't get myself into it. Thank you in advance for your time and support.