You’ve lost 3 stone. That’s an AMAZING achievement. However, you’ve clearly got to the point where you need to make another substantial change in your lifestyle to progress more.
Firstly, you need to track your calories and get the weighing scales out to make sure you’re not cheating yourself. This is also important to make sure you’re eating enough. If you look at my iPhone estimate of calories burned and compare it to my calories logged, I’m at 12,221 burned and 12,604 consumed for the last 5 days. The phone isn’t accurate for many things and my logging won’t be absolutely perfect, but I shouldn’t expect to have lost weight in this time period. Perhaps even put on a couple of grams. The reason I’ve mentioned it is that I’m currently sat with 45g of green and blacks chocolate in front of me. If I had really looked at my weekly input before going in the cupboard, I might not have had that tonight. That’s pretty much been the difference between gain and loss this week. Log milk in tea and condiments, get really into the detail.
The exercise routines should come a very distant second to your diet. Absolutely do more exercise, that will allow you to consume a bit more, but the answer will remain a real honest dietary sort out. As mentioned, if you like weights in the gym, get some compound lifts in. Squats, DL, bench, military press. Get on the machines once you’ve done those. If you want to increase your numbers, you’ll need to increase your calorie input. Think carefully about what you’re going to the gym for. Are you after strength, size, shape, fitness… etc etc? The best way to get fit is to find an exercise that you love (seated leg curls aren’t anyone’s favourite).
Good luck!