Lisa, one of the unfortunate things about waxless XC skis like the BC 70 is that for many people they work well…under a very narrow range of conditions, generally flat to gently rolling terrain and snow with some moisture content. It sounds like those are the conditions that you are using the skis in unless you are on hard-packed or icy trails. I’m not sure why you’re not getting better grip on flat terrain. It might be technique to some degree, though if you did OK with the previous skis (also waxless?) technique ought not to be the issue. At your weight is seems like you did get the right length. What is the snow like where you are skiing? (Heavy and wet…?). I have heard of people applying temperature-specific kick waxes to waxless skis in front of the fishscale pattern to try to get a little better grip. Haven’t tried that myself.
Some people who really like your ski seem to be either a little heavier for the ski they are on or are using it with 3-pin telemark boots/bindings, which will allow one to apply a bit more leverage in the front of the boot while climbing.  I also wonder if your ski came with the binding premounted, or did a shop mount them for you? If they are shop-mounted, I wonder if the binding wasn’t mounted on the balance point, which would mean your weight isn’t being optimally distributed?
Fischer, Salomon, Alpina, Madshus, and Asnes also make waxless BC skis in a variety of widths, and some of those skis use a nylon or mohair strip in the kick zone instead of the fish scales. That might provide better grip, but you’d want to check reviews. Over the years I’ve heard of people who weren’t happy with their Fischers, and other folks who loved them, so go figure. I once took out a pair of demo Fischers and tried to ski up the very gentle beginner slope at the local ski area – couldn’t do it, but the snow was fresh and very dry. My favorite waxless XCD skis are Karhu 10th Mountains – now Madshus Epochs. They are more about the “turn” than the “tour,” but they tour well enough and turn better than a ski with less sidecut, and they grip pretty well in most conditions.
AFA skins, they work because they have a one-way nap that allows you to glide forward but not slide backward. They are usually made of nylon, mohair or some combination of the two. They commonly attach to the tip and tail of the ski with loops and clips, but some companies offer proprietary skins that hook into slots or holes in specific skis. For many years Black Diamond sold short half-length skins called “kicker skins” that are ideal when you want a little more grip. Unfortunately, BD seems to have discontinued them and I don’t see any availability. Most skins now sold at outdoor shops are very wide (90-140mm) and quite expensive; they are marketing to the AT crowd.
Another option for you might be to go back to a waxable ski, one without the grip pattern on the base. The upside of waxing is that when you get it right, you can glide more efficiently and grip pretty well. The downsides are that sometimes it takes awhile to figure out the right temperature/color of wax to use, and if conditions change you get to change your wax.  Honestly, some things are just plain getting hard to find these days: narrow skins, waxable skis, and even temperature specific kick wax for those skis. The pandemic has made things even harder to find this season.
Finally, I would never try to mount my own bindings on any ski. I would rather pay someone who does it all the time, and if they screw it up it’s on them. I don’t want to mis-drill or poke extra holes in my skis or get the mount position wrong. There are probably plenty of DIY videos on how to do it yourself if you want, but I’ve seen the pros mess up enough that I wouldn’t try it myself.
If you don’t live near a shop, you could just call a shop in the part of the world where you are and ask for their nordic backcountry ski expert, try to pick their brain on why you are having these issues.  I’m no expert, but I have skied for a long time on many types of gear, and I’ve tried to provide a little insight on why you might be struggling. There is a website called TelemarkTalk.com that might address your issues, or you could post a question there. Maybe some of this is a little helpful.