Yes I think it's enough
Because each Bitcoin can be divided into 100,000,000 units Satoshis sats. 1BTC= 100,000,000 sats, so this means that there are effectively 2.1 quadrillion Satoshis in total
So even if Bitcoin gets to a very skyhigh price, there will be no need to hold a whole Bitcoin to your self. We can just make transactions and save in tiny fractions. so that's it, if Bitcoin had an unlimited supply like regular Money, it would lose purchasing power and value over time
I think this is one of the most important and strongest point of Bitcoin. For sure Bitcoins can be spent in smaller units which makes it very useful for a very long time in the future.
However I honestly think that Bitcoin transaction fees should go down. Many people would are go that it's already low, but compared to the mainstream banking industry, the fees is still high expect overseas transaction.
21 million is fine and I don't see any major issue there. But in future when Bitcoins price will go higher, some tech updates would be necessary.