In the long run anything is possible, put in the effort/intensity, and you can gain a lot. At 5.75 x 4.3, I would make stages of goals.
Stage 0: Get familiar with PE, learn how your body responds. Then build a routine.
Stage I: 6 x 4.5
Stage II: 6.5 x 5
Stage III: 7 x 5.25
Stage IV (Ultimate!): 7.75 x 5.5
These gains are possible if you put the time into PE. As you grow, you will hit your different stage goals. As you pass them, you will become more & more motivated. Good luck.