Sarals, I would first switch to an 11-28 cassette for an easy improvement in gear range. That, along with improving your strength and climbing technique, may be enough to get you up the hills better. Climbing technique is a deep topic and the subject of many threads and articles. Search the forums and Google for more advice than you can digest.

My top tips for climbing are to do it often and to concentrate on spinning circles with your feet to get more power out of your pedaling. It may help to visualize scraping mud off the bottom of your shoes as each foot moves rearward through the bottom of the pedaling circle. When I feel my cadence dropping on a climb, I concentrate on pedaling full circles and will often see my speed start creeping up.

Next step would be a rear derailleur switch to a MTB one (Deore, SLX, XT etc.) and a MTB cassette with a 32 or 34 tooth largest cog.