My two cents:
1. The VO didn't say ACS membership is tricky. But the USCIS thinks such kind of memberships are too cheap. They don't count them if your categry is EB1 or NIW.
Are you a member of the organizations like Sigma XI? If not yet, is it possible for you to get at least one of such memberships shortly?
2. How about your work's impact on the your field? - -citation by peers? reported by some media? highly positive comments/evaluations from big names of the field?
3. Have you ever reviewed papers for some national/international journals by direct invitation?
4. Try to illustrat that your research has made a major breakthrough by collecting a couple of extemely strong letters from big names in the field
I fully understand your current situation. It is truly tough because your category is EB1a. Frankly, the amount of your papers is not so impressive for your specific petition, thus you may even not acclaim that your publication record is strong enough if none of the papers have appeared in the top journals such as Nature and Science.
Try your best and good luck!