In your position, I think you should put some serious thought into taking a year off following graduation to do some full-time post-baccalaureate research before applying to top tier Chem programs. Perhaps you could continue working in one of your undergrad labs as a research assistant/technician, or options also exist for short-term post-bac research programs that are specifically designed for recent grads looking to gain more research experience before applying to grad school (ex. NIH post-bac program https://www.training.nih.gov/programs/postbac_irta).
I'm currently in the middle of my year off, having recently submitted my PhD applications for top tier Chem/ChemBio programs. I derived significant benefit from taking a year off for the following reasons:
-Grad admissions committees like to see full-time research experience following graduation. With more and more applicants having a M.S. or multiple years of research experience following their bachelor's, it's getting harder to justify accepting PhD students straight out of undergrad. Having post-bac research experience helps a lot, although it definitely isn't necessary for getting accepted into top tier programs immediately after undergrad.
-An additional year of full-time research experience = a lot more potential opportunities to engage in research projects that could lead to publication. And while having peer-reviewed papers at the time of application is definitely a plus, having manuscripts in progress is the next best thing, as long as your LOR's can support your claims. I wouldn't get too caught up on not having any publications. They're just one way for admissions committees to gauge your aptitude for research. There are other ways to demonstrate this aptitude (i.e. your LOR's). The additional year of research also gives you more time to build up your relationship with your PI, which will hopefully translate into a kickass LOR (the recommendation from your PI is arguably the single most important piece of your application).
-Being able to fully devote your attention to your grad applications during your year off, instead of having to balance them with your senior year Fall semester courses, can do wonders for managing stress and ensuring that you have adequate time to polish and fully flesh out your applications/SOP's.
-Lastly, remember that once you start a PhD program, the next ~5 years of your life will essentially be spent as a research slave with very little downtime to pursue personal interests. If you take a year off, after you get all your apps in, you pretty much have the next half year to do as you please. Don't forget that we're in our 20's (our physical peak in life) so take the opportunity to live it up! Most grad students are approaching the age of 30 by the time they finish their PhD, if not older.
Hope this helps.