Are you able to add an extra year to your undergraduate studies? My husband did MechE and Chemistry as a double major but had to add a fifth year to finish his Chemistry degree. For him it made sense. If it’s financially feasible, you can look into the two course schedules that interest you and see if it’s possible. Have you taken quantum physics yet? That was the point in my engineering undergraduate career that I was not sad to part way with Physics. But I love Astrophysics and Cosmology so I get your desire to keep going. Does your University have a strong Astrophysics concentration? I can’t offer career advice as I’m not in the field. Good luck and I hope things work out for you!