Andrew, after some thought about where on 20m you were activating, some of that CW you heard may have be digital stations sending a CWID and not replying to your calls. They just want to ID and so blast it out as fast as they can before moving to the next digital QSO. The other CW may have been telling you (probably impolitely) to QSY out of the digital suband, at least on 20m if you were on 14.070-14.090.
Anyway, what doesn’t kill us makes us stronger. So hopefully this will all be good practice for your next trip out. Operate near the well known CW QRP frequencies will help. I try to operate 14.055-14.058 and 14.062-14.065 CW and not too close to 14.060. Whilst I may be QRP, many of my cashers wont be, keeping that small window centered on 14.060 clear allows QRP-QRP (often rock bound) QSOs to take place with less strong signal QRM from my chasers. Likewise for 40m 7.025-7.028 and 7.032-7.035, and somewhere around 10.118 for 30m.