A standard keyboard has around 104 keys, but some smaller form factors might sport 80 or 60-ish. I'd lay good odds that your keyboard is somewhere in that realm, but there are enthusiast boards that make do with far fewer. So-called 40% keyboards are increasingly popular, and one of the most well-known is the Minivan from TheVan Keyboards. This keyboard is small, but it's more powerful than you'd think.
A 40% keyboard has all the standard alpha keys, but many of the other keys are missing or smaller than usual. These boards all have varying ideas about what keys you need, but I think the Minivan is the best for a few reasons. Rather than use a full-sized spacebar and enter key, the Minivan uses a split space design that lets you have both space and enter on the bottom row. That frees up locations for function keys and mods in the Minivan's small footprint.
The Minivan also has several keys that are programmed to have different functions depending on whether you press or hold them. For example, the Fn toggle on the right is the quote key if you just press it, but holding it down triggers the assigned function layer. Function layers are a big deal on the Minivan, as you'd probably expect. It doesn't even have a number row, so you'll need to flip between at least two different layers to access all the usual keyboard features. However, you can get extremely efficient with enough practice. Every keyboard function is accessible within no more than two keys of the home row, so you can dramatically cut down on hand movement with a Minivan.
Like many custom keyboards, this one is fully programmable via the TMK firmware. There's an online config tool where you can visually define your layout and function layers. Flashing that layout to the board is a snap (as long as you've got the necessary program installed on your computer), and you can change it as many times as you want.
The Minivan is a custom kit, meaning you'll probably have to build it yourself. Luckily, the Minivan only has around 40 switches, so it's a great first soldering project. You don't even need a plate for the switches, so the build is really fast—solder the switches, screw in the stabilizers, mount the PCB in the case, and plug in your keycaps. TheVan Keyboards even sells keycap sets that are custom designed for the Minivan's unusual layout.
I wish I could tell you I used the Minivan all the time, but I'm personally more comfortable with a slightly larger board in the 60-65% range. That said, I know people who use a Minivan full time, and it's a great little keyboard. I often bring it with me on the road, and it's kind of amusing to see how people react to such a tiny keyboard. You can give the Minivan a shot for under $100 with a PCB and 3D printed case. The nicer versions with an aluminum case start around $200. It's also 100% made in the USA.