Can I keep going?

I started the journey 4 jabs ago (3 weeks) and lost a good amount of weight on 2.5 mg, however my doc prescribed me the 5 mg pen to start out with 2.5 for 2 weeks then titrate up to 5. Well… I already lost 8 kgs and I feel all the positive effects on 2.5 so I did not titrate up. Now I will be left with a lot of extra liquid in the pen. What should I do? Titrate up for next jab or keep using the pen after the 30 day mark? And if so, how long is it good to use? Thank you for your help!