That is not a very long time at all. After my first year of playing the game, I was still missing over half the legendaries. Thing is, it didn't bother me, I thought that how the game was and enjoyed advancing at my own pace...until I visited the forum.
Here I saw people mentioning x3 or x4 of the same legendary (webspinner, it was when team bonuses were introduced and she was a thing), as if it was the most natural thing, and I came to a shock. It turned out that some people had the level of resources I could never imagine possible - and not just by spending money.
The ending was good, at least. I found out the deciding factor was not my playtime, nor money, it was guilds. Get into a top guild, and you'll have everything in no time. Stay in an average one, and you better forget about completing your collection, and just play as if it's not possible. So I did [join a top guild], and indeed, after a month or two my collection was complete. A few months further, and I was having more and more of my cards to mythic. Getting the base mythics when they came was no problem either.
So my advice to you is this: Choose your route.
If you have to have everything - no way around stepping up. Find the best guild you can somehow fill the requirements of (where 'best'=does the most legendary tasks), or possibly up your game to squeeze in the very top ones. Friends and values be damned, gotta catch them all!
If you want to play the game at your own pace - forget about all these wrongly-colored troops in your collection, ignore all those forum threads full of bragging about having every mythic. Those aren't you, they are all top-guilders. Instead, concentrate on what brought you to love the game from day one, when you hardly had anything. Enjoy the 3-match system, the events, the challenges, the relationship with your guildmates. And no, the "Show All" button in your collection does not exist. Never, ever, press on it.