There are so many things that are troubling me about your original post. I don't know what the age of majority is in UK, but in certain places you would be considered a minor under law. This already poses a problem if you are trying to operate on exchanges; as they are not allowed to serve minors. This problem is made worse when you are using someone else's information in order to illegally access an exchange as a minor, and then made even worse if your mother is aware and acting as an accessory to this type of behavior. Unless your mother is actually the account holder making these purchases they very well could be illegal, but again I don't know your laws so you would have to figure that out for yourself.

That being a disclaimer, my biggest worst of advice would be to take control of your coins and stop allowing them to sit on an exchange. There are endless horror stories of exchanges and exchange accounts being hacked, leaked, deleted or disappearing entirely; if this happens you will have no recourse and be forced to bear the cost of whatever you left on the exchange. Having control over your coins means having the private key associated with whatever address(es) you are holding coins on. Download a wallet that allows you such control; Core is what I use, some use Electrum and there are many other solid alternatives. Exchanges are not a good hot-wallet, and if you ever get a substantial amount of bitcoin that you would be very upset losing then you should look into cold-storage wallets, which are hardware wallets much safer than any exchange, or regular hot-wallet.

There is a lot for your to learn, but you are approaching this somewhat decently; hold your coins, always assume it is a good time to buy BTC, build a stash of them and don't be tempted to get into day trading until you have practiced religiously for a long-time before using your real money. Bitcoin is a long-term investment, and a technology that is very sluggishly being adopted and garnering the value and attention it will undoubtedly attain.

This thread might be a better conversation for the Economics, or speculation section by the way; Beginners and Help is more for trouble your are experiencing or questions relating to other things.

While we may be up at $8k from $6k, it's important to note that the major resistance is around $10k levels. Without momentum or an attempt to break $10k soon, we could see price fall below $6k.

You should look into and study markets in general before investing as everything essentially has risk associated with it. The crypto market is one of the highest risk markets out there with large swings up and down. They are a virtual currency so they have no earnings, just move based on peoples sentiment and technical movement based on the charts.

So you should look into some technical analysis which is studying the price movement of the asset on a chart. (Tradingview has good charts for cryptos)  If you go long, you do not want to purchase when the price is declining as it can continue to drop further and you will lose money. So people wait for an uptrend before they purchase,,,,this is easier said than done and takes some charting analysis.

There are a lot of good books on technical analysis, check some out.