Draw current customers from selling avenues like Amazon to your website?

I sell clothing (mostly graphic t-shirts) on most of the major selling avenues like Amazon and my current sales on said sites DESTROY my own website sales. Now I understand this is probably expected given their traffic but I mean the major selling avenue sites I use combined for 85% of my total sales. If I were to lose any of these accounts for any reason I would be In for some very rough times. I don't like putting all my eggs in one basket and I really need to stop this trend. I have had my own site now for 9 years and I have tried year after year of getting my website to compete with my other selling accounts only to see for the first time in the past 5 years my website sales drop over 30% this year! I have tried everything you can think of including, site revamps, social marketing, adwords, SEO services, blogging, youtube reviews, expensive Instagram product shout outs, contest giveaways, sponsorships, free shipping, 800 number so customers feel safe ordering and can even give us a call, email marketing, putting sales coupon fliers for my website in with orders I ship out from Amazon and the likes, lowering the prices to more than half of what i sell it for on the major selling avenues, you name it i have pretty much tired it. I just don't understand why I can sell so much on the major selling avenues but they won't shop with my site even when I give them huge discounts? Has anyone had any success with driving customers from the other heavy hitter selling sites to their own web stores? I would love some advice and or feedback on this. Thank you in advance!