Trying to Get Better!

Practice and experience do make you better at any skill. You may not recognise it, but you are learning and growing through simply playing the game.

I think the fact that your matchups are so varied does more to help you than hinder you. If you just play against the same types of decks all the time, be they meta decks or your friends' jank piles, your testing and experience becomes too focused on one specific environment with only one type of play.

Exposure to variety will make you better. To make the most of it you may need to be more analytical rather than passively playing the game. Look at what matchups work well for you and what matchups go poorly. Analyse which cards you play work well and which are suboptimal, and which cards your opponents play are the most problematic or disruptive.

Make paper notes if you can. Sometimes having the data in front of you in black and white can really help expose information you might not have seen otherwise.

In short, it is not the games you are playing and exposed to that are bad, but maybe you need to spend more time examining and critiquing your own play afterwards if you want to improve.

Otherwise, if you genuinely feel you need to explore other methods of improving your play, coaching can certainly help you do that, but it is not the only method.

Before spending money on that, do you have any other friends who play the game? Do you play in paper?

If so, consider playing and testing with them. You can deliberately try playing decks with and against decks you wouldn't normally play or have bad matchups with to gain more experience and learn their weaknesses.

If you are just playing with friends at home and not an official setting like an LGS, it is fine to proxy cards to try out decks or new cards before you buy them. Testing would be hideously expensive if you had to buy every card.

Whatever you decide to do, I wouldn't be so hard on yourself. All play can be a learning experience. What matters is how you go about analysing and learning from it afterwards.

Good luck.