So if I then miss the brief period after shkia that you say I can still daven mincha, then what do I do? should I then daven maariv and then make up mincha?
ב"ה Shalom Yes. If you miss the time for Davening Mincha, you say Shmoneh Esreh twice at Ma'ariv. The same applies for Shacharit and Ma'ariv as well. A Tefilla that is missed due to circumstances beyond your control, or due to simply forgetting, the Shmoneh Esreh is repeated at the following Tefilla. (See שולחן ערוך או"ח סי' קח) All the best