I am 23 yrs old, weigh 59.5 kgs and have a height of 160cms. I go to the gym regularly and work out for 45mins?

I go to the gym regularly and work out for 45mins including few weights. Moreover, I walk to my uni everyday which totals to 6kms. My upper part of the body seems to be fine as I wear clothes of the size range (UK)8-10. Its only my bottom that is quite prominent. How much do you think I need to loose more and my lower half just does not seem to reduce.