At the very beginning you were sitting second wheel and dying to hang on. Second wheel is not a great shelter position - it might have been better to let the guy go and ease back into the field, sit maybe 10th-15th wheel, behind at least a 3-wide bunch of riders. Sitting behind one rider doesn't offer as much shelter as sitting behind a 3-wide bunch of riders, or even 2-wide. Sitting behind more-than-one-wide means you get shelter from the wind even from the sides. At the back you get sucked along, but those roads (yellow line rule not in effect) seem pretty narrow, the pace pretty fast/steady, so I imagine it would have been hard to move up or it'd have increased the chances of getting caught behind a crash if you sat at the back.
Overall I think you did fine, it's just honing your tactics to your strengths/weaknesses. 6th is a great place in a race so you did great. I'd take a 6th any time I could, except the rare occasions where I get better than a 6th. All the wins and stuff you see here on BF are anomalies - a top 6 is a great result.