Yes! You did very well! This is an excellent base for building your high school GPA and record. Take a hard look at how you approached the work in honors geometry, and think, “Did I do all that I could have? Did I practice the problems on a regular (possibly daily) basis? Did I put in my best effort?” If the answer to that is yes, then you should be PROUD of that B+. If the answer is no, then consider what you can do to get the A next semester, and set yourself up for success by doing just that. BTW, some people just have more of an algebra brain than a geometry brain, and vice-versa. It’s very common for people to find one of them easier to do than the other.
In addition to getting good grades at a challenging high school (which you already are), you should be thinking about what you might do to distinguish yourself from all the other highly qualified applicants. You say you’re interested in engineering. Do you have any idea what type, yet? Mechanical, Bio, Chem, Electrical, Civil, Geotechnical? What are you good at? What are you interested in? Think about how you can distinguish yourself while in high school in engineering. Engineers DO stuff, rather than just have good grades. So you need to get involved in some kind of project-based or competition-based engineering, like robotics contests, or bio-engineering research, something, so that you can put, “I placed high in this competition”, or better yet, “I got involved in a research project at the nearby research institution, and wound up named author on such and such”. Honestly, this is probably more important than the good grades and test scores (but you also need those grades and test scores). You want to be in that cohort where the admissions committee says, “Wow. Look at that interesting research project she did.” Or, “This girl placed very high in this top robotics competition.” And then they look at your grades and test scores, and say, “Oh, she’s also a solid achiever. We want her.”
Thirdly, you’re going to want to do really well on the PSAT - try for National Merit. If you were to begin preparing for that over Christmas break and over the summer, when you’re not under such school pressure, you could very well put yourself into the running for National Merit. It shouldn’t be, but there are certain schools for whom this credential means a LOT, when it comes to admission and merit money. And most kids do not start thinking about test prep until it’s too late to affect the PSAT, which is taken in the early fall of 11th grade.
I do NOT think that you are being overly anxious. I think that you are young and planning, and that is a good thing. This was a great first semester! But try to shift your focus forward, rather than backward. That B+ was nothing to be ashamed of. Now start figuring out how you can get involved in a project or research that will set you above all the other people with good grades, and will also help you to explore and develop your own interests within engineering.
Another thing - start looking for summer engineering programs for high school students. There are some that are geared towards women, to try to encourage women entering the field, and of course there are also ones that are for both men and women. These can be found at many colleges all over the country. Many also have scholarship aid to help you afford them. Teachers at your school may know about these, so ask them. Also ask at the counseling office - they’ll know about some of them, too.