Workout length (45mins-1h)
A successful workout shouldn't really exceed more than an hour to an hour and a half. 45 minutes is great, your body can push 100% throughout that time. Anything more and you start to slack off or give less intensity on the other exercises.
Workouts > 1 hour 30 mins
Personally, my trainings go from an hour and a half to two hours (stretching and abs included). Although, I eat very well and provide enough carbohydrates so that I don't feel drained. I drink intra-workout shakes (which provide BCAAs, Carbs, etc) to help me stay hydrated.
What you can do is switch up your exercises, try something new. You need to perform things your body is not used to - that way it will adapt and change accordingly. If things get easier, yes you can definately add in some more exercises; like 15-30 burpees or plank exercises.
If your goal is a stronger core, here are some intense abdonimal exercises I perform and suggest to my more advance clients:
- 10 v-crunches (legs elevated off the ground slightly)
- 10 single-leg v-crunches (legs elevated off the ground slightly)
- 30 seconds with legs and upper body slightly elevated (lift arms if possible)
- 20 crunches
- 15 bicycle crunches
- 1 minute plank
As for the protein, yes your body should intake more protein than the usual person. You're excerting more energy and your muscles need to rebuild. Protein will help you do that. You should take about 1.5g of protein pour kilogram of bodyweight. Knowing that you're 58 kilos, you should take approximately 87 grams of protein per day.
Keep in mind, do not take all the protein at once or else you will just poop it out. Separate it throughout the day for more successful results. Your meals also have protein so try to balance it out with protein shakes if needed.