Suggest Methods To Improve Penile Erection

i am a 21 year old guy.2 years back i was 110 kgs but then i joined a gym and lost arong 35 kgs...but i beleive over the time i have lost that libido and at times have lesser hard-ons and erections while making out...
i am stil a virgin but then while foreplay i dont that longer hardons..
sometimes when i mastrubate and morning time i have proper erections

also since like 2 months i m experiencing frequent urination like 5-6 times a day
can you please help me why is this happening and how can i improve on my erections