GPA 3.70 MCAT 38 limited Clinical Exp, gap year?

I'm a chemistry and mathematics double major and currently a junior at a top Liberal Arts College. I'm planning on applying only MSTP and I was wondering if I should take a gap year.

I have limited volunteering, tutored high school students for a summer and a semester, shadowed two doctors for a total of 2 months. I'm the president of some clubs, but nothing that notable (chem club, chess, etc.)

I've done chemistry research every semester since I was a freshman, and I've had two articles in a peer reviewed journal of moderate impact factor (2nd author for both). I've also done independent research on helping undeserved population overseas through a fellowship I applied for (I actually got to visit less developed areas in China and Indonesia), and I was able to present my findings at a conference. I've worked at a translational biology research laboratory for two summers, no publications.

My LORs are pretty strong, but are only really from my research experience. My concerns are my lack of clinical volunteering, GPA, and my MCAT score. I took the MCAT twice, I was having an off day the first time I took it and got a 29S (11PS/10BS/8VR) and then got a 38R (14PS/13BS/11VR) after retaking it at the next available time. I realize my GPA (3.70, 3.65s) is about average for an MSTP applicant but I hope my somewhat extensive research experience will make for it. I also have two W's one from organic, which I retook and got an A, and the is other from a 400 level math class that was just went over my head. I've had an upward trend from a 3.3->3.7 (every semester after the first was a 3.8+, except for one 3.6)

Should I take a gap year to improve my clinical volunteering and my GPA? I'll be working in the translational bio lab if I chose to take a gap year. Any advice is appreciated, thanks in advance.

No, it was volunteer, about 3-5 hours a week. In total I have around 6 months worth, I could probably add in 50-75 more hours. All my volunteering is tutoring based, through a college-local community volunteering group. The hospital near my school isn't very open to student volunteering, so the only clinical exposure I've gotten is through my two shadowing opportunities. Would it be beneficial to try to get in some volunteering now and during spring break and also during the summer?

I would prefer getting into a highly selective MSTP program for selfish reasons (I do realize that less selective programs still have great research opportunities); enough to do a gap year to improve my app. Though if I had a decent chance now I wouldn't think it would be worth it.

I'm currently doing research that will potentially result in a first author publication but I doubt it'll be done by this summer, a rapid correspondence would probably be pushing it too.