Have glasses getting contacts soon, have some questions?

So i am 13 and i wear glasses i am near sighted (can't see far away) and i will be getting contacts very soon. But when i was little reading or at the computer i would look with my glasses and when i would take them off, it would make reading a little blurry, now i don't do that because it ruins my eyes when reading. But if i am at school reading with my contacts on won't it ruin my eyes? because contacts is just like glasses but you can't take them off. then i would be getting bifocals when I'm like 15 which isn't cool.... So do they have type of contacts that doesn't make my eyes vision up close worse? And if they don't, won't my eyesight be getting worse and worse every time i read or am on the computer with my glasses/contacts?

Please help!! You will get 5 stars if your answer helps me and thumbs up too!(: