You'll never really feel more experienced, I think, and you probably won't notice you're drawing faster. You'll just be drawing pages some day and think "...ugh! I'm so slow at this!" and then realise that even though you think you're slow, you're actually twice as fast as you were 5 years ago. Or you'll be there thinking how the rate at which you make pages hasn't changed from when you were younger, but then remind yourself that your new pages are much more detailed, so it actually has but you're using the time to make the pages look better.
Sometimes it's not that you're just faster at turning out content so much as like... the content you rush out quickly or make on an off-day where in the past you might have been like "ugh, I can't write/draw today" is much higher quality. The base level of your writing and drawing goes up more than the top level. If I just show the very best panels and pages from my old work, people might think there isn't that much improvement... but if they read full comics of mine, they'll definitely see how my current work has much more overall polish on the regular panels and pages that tie things together, clearer storytelling and better setup of elements to pay off later, just the overall consistency of my work is better, because I focused on building on my weaknesses rather than doubling down on my strengths.
You won't be able to tell so easily yourself, but keep trying to write and draw things you find hard; script out a complex sequence, or write an emotional scene, or draw a detailed establishing shot... and at some point, you'll be doing something like that on a page like it's no big deal and think "...I used to really struggle doing this!"