Hi scotto, im almost your age im 23 and ive never been coached by anyone in any style, i have also been a martial arts fan all my life and like you im also training with friends teaching ourselves.
If you have a bit of experience and love for the game you can defently improove from your own teachings and the support and help of your friends.
Oviously it is a lot more difficult without experienced coaches and you will make lots of mistakes but thats how you learn and you will also develope a unique style.
Here are some links to some training videos we made just yesterday, they include sparring, padwork and freestyle bag workout, we train straight out of my garage.
So if you could make a whole room in your house that would be awsome, it defently wouldnt hurt.
Weve only just begun our training journey this week so they are our first videos, we've only taught ourselves to mix it up through watching and studying ufc fighters so bare with me, hope they are still inspirationl enough.
We still have to improove 100% but you have to start somewhere.