I've never had a tire gauge except on floor pumps. I just squeeze the tires after inflating to the pressure I want at home. Remembering what that squeeze felt like for the rest of the ride isn't hard. And if I get it wrong it will be obvious very soon. So I just stop and let a little air out or take my frame pump and add a few pounds. (Now it does appear to be popular to sell bikes that are hard to put frame pumps on. I get as an engineer that the time and effort it takes to design that ability into the bike costs money and precious brain time. Still, I see it as just lazy,sloppy, and/or poor engineering not to incorporate the requires 3 grams for a pump peg onto a multi-thousand dollar bike. At least until the day when those manufacturers can offer bikes with tires that are not subject to air pressure loss.)

To the OP - get in the habit of squeezing properly inflated tires. Your fingers will learn what good riding pressures feel like. You will even start appreciating that different tire widths, ride types and tire types want different feels.

Ben