I'm not really trading, but who doesn't like more BTC by selling high and buying again "low"?
Am I wrong or is the mempool being pretty empty a REALLY bad sign for the 50%+ in Price?
Is this the last high for this year? Or am I being too paranoid after 2017

That's normal to be paranoid when you got worst previous experience last 2017, it kept coming back on your memory and no one was exempted of it. Price usually go uptrend as it rises, then tx fees also commensurate as percentage also follows for transaction.
If see some bad signs, then we're free to decide nobody would stop us whether giving up or pursue to risk our holdings.