Just a suggestion here: the first page of your newsletter is your sign up form. Kind of a horsetail before the horse before the wagon arrangement. Based on your newsletter first page, why would anyone want to sign up?
What are they getting for signing up? You need to let people know — in concrete detail, like a sample article or selection of articles. Put a LINK ONLY to your sign-up sheet alongside your best articles, and put the articles FIRST. Have a TOC [table of contents] to your most recent work, and then a full TOC to everything maybe 2nd or 3rd page, or at the back. Given how much work you have maybe that would be a TOC to your topic sections.
Take a look at how others organize their newsletters. The best ones have a formula for what comes first, middle, and last. Just like any article.
That’s just a suggestion. I’d have to spend much more time with this to give you the best & most complete advice. If you want that…well, let’s negotiate price.
You could probably fix it up on your own by thinking of your publication as being structured like an article. First you have pieces to pull people in. Then you have your middle, then of course, your end [like yeah…so what else is new?!] For those who look at back pages first (there are quite a few), have a back-end article that pulls them toward the middle.
Very likely there are newsletter/magazine design articles on Medium. Regardless there’s plenty out there to help you if you prefer the do-it-yourself route.
Take a look at other people’s designs to see if there’s anything you can pick up there from the ones you really like.
I have a whole lot more to suggest, but as you well know, time is money. Well, time is money when you do it right.
Best of luck!