I'm using Finasteride 1 mg and I want to know if it's safe for me or not?

The answer to this question will depend on your personal genetics.  
Firstly, Finasteride is a DHT blocker known to block up to 60% of circulating DHT in the system (depending on dose).   Finasteride does NOT grow hair. At 1mg it will likely block less than 60%.
There are better more effective DHT blockers available on the market now.
One thing to make sure when taking any medication like Finasteride which affects your hormone levels is to ensure that you do blood work before being prescribed a DHT blocker to understand what will happen to your hormones once you start taking it.  For some people the extra testosterone that is created by blocking the DHT conversion process will convert instead to Estrogen and cause side effects.
Please make sure to see a hair loss expert who will provide a thorough analysis of your hormone levels and prescribe treatment based on those, rather than a one size fits all solution for the "average" population.  You may be part of the 10% who end up with side effects due to not understanding your personal chemistry prior to prescribing.

The vast majority of studies, and male population, show no significant effect of finasteride on male fertility.  Men who have an underlying problem that may affect fertility, such as a varicocele, may see a reduction in sperm counts or sperm motility.  A few cases from infertility centers, report reduced sperm motility.