FH?

I’m a 30’m , I have never done any health check until a week ago..

While all every data in CMP/lipid test looks good, the LDL is extremely bad.

My total chol: 312, LDL: 249, and HDL:55

My doctor said it could be FH, but lets give it few months to recheck.

My lifestyle has been poor, nearly no exercise / veggie and consuming mostly junk /fast food like fries and fried chicken, cheese, ramen, instant noodles, and some chinese BBQ, and some rich sauced pasta, coffee lover, bread, chicken with skin, hotdog / sausages, etc… But i'm not fat, 22BMI, 170cm with 63kg.

So my question is If I really have FH, would these lifestyle has already brought me to another level of high? and would my LDL level achievable for non-FH patient, or it's high enough to justify it will be highly likely a genes issues?

I have been adjusting my lifestyle to plant based since 10 days ago, and for cardio I have been doing one hour daily since then… rechecked my LDL at home , it goes to 241 now - maybe actually just a noise. Will give it more time to see…