to asnwer you rQ about your gearing - here's whats listed on Amazon for the Men's White Libero - has Cassette: Shimano CS HG30 8 Speed 11-30
Crank: Prowheel Alloy Arms 170mm 42/52
based on this info, you have a full range of gears for just about any ride terrain.

go to sheldon brown;s website - the gear calculator - and get a gear chart done for your bike - I'm used to gear-inches, others use gear development...
try to undertsand what that chart is telling you and you'll go a long way to learning how to use your gears for riding.
Search BF road for a threads on gearing. From those you'll piece together a lot of info which you can apply to your ride.
sounds like you're already 'spinning' gears more than mashing - that's a good start.
Keep spinning, get a few thousand miles into the legs before worying about 'speed'.
The best thing you can do, which doesn;t cost a lot, if anything, is get to ridin with an established group/ride. Be observant, ask questions, watch the good bike handlers, the smooth riders. Read a lot
Looks like you have a serviceable machine - resist upgrading parts - save the money for your next machine. Buy good tires - good doesn;t mean the most expensive.
8 spd - 10 spd
10 spd is current, but the 8 spd you have is fine and covers all you'll need for a while.
10 spd will not make you faster or a better bike handler or a smarter rider.
riding a bike well is a program in self-awareness and patience. learn an appreciation of just riding and being on the bike, don't get consumed by speed.
8 speed is fine, I can still get a nice turn of speed out of my old iron with 6, 7 or 8 spd rears...
and if it all sticks, when you get to be 60+, you'll still feel and act like a 30 something