I'm very much a fan of the concept "form follows function". To me, appearing masculine is less about facial structure and body type, and much more about how one composes themselves and the actions they perform. Now, that's not to say you don't have an objectively feminine face, if it's said you have a remarkable resemblance to your mother, you probably do. However, it has been my experience that this will be heavily overshadowed by what you are doing and how you as a person are perceived.
For example, I had a friend in high school who was short, skinny, and had a somewhat feminine facial structure. NOBODY I knew thought of him as feminine, though. He was a farmboy, through and through, did a man's chores, did things typically associated with masculinity, behaved "manly", and I tell you... he was one of the few people at that school I'd not want to get in a fight with. He was a star wrestler who would fireman slam dudes twice his size on a regular basis. To all of us, he was masculine.

So, if you do "manly" things usually by default, and do so to achieve your objective in as quick and efficient a manner as possible (within reason, and without stepping on the boundaries of others), and that's what you ENJOY doing, if this gives you satisfaction... then stop worrying about your immutable features and carry on with your day. They are ultimately inconsequential to what you do and how you do it, as are what people might say of said features. Set yourself as a stone and roll through their observations like a boulder down a hill, they'll get out of the way and you'll do what you want. Do not pause and ponder what is meaningless to your goals. THIS is, to me at least, what it means to be masculine. And form follows function. Be masculine, and you will appear so.