Well,even though the duration of your relationship is not known but notwithstanding
I am an advocate of age is just a number in a relationship, cos the age doesn't really matter what matters most is the person behind the age.
I won't advice you or any other person out there to be blinded by their feelings and emotions to the extend of proposing,engaging or even getting married to someone you want to spend the rest of your life without knowing everything about them, mind you marriage is the biggest life contract and also a life time union. Cos you don't just wake up and rush into it. When you feel like.
If I understand you, and I quote " am afraid of why is she still single. Am confused whether to go ahead or break the relationship" my dear friend I want you to know that no lady in her 30s will ever play hard to get without a strong reason behind it and in most cases they have had their trust betrayed, their heart pierced, their feelings taken for granted,their hopes shattered or have find themselves abused and many more. and if you ask me I see no reason why you should be afraid, cos you ought to have known each other well enough before deciding to propose to her unless you are planing to propose to someone you just met on your way home after a busy day at work.
So my advice to you is talk to her, and get to know her better, including
#everything she likes and unlike
#her past
#her family and she herself as a person
And mind you in the course of doing this follow your heart but use your head and please beware of what people say about her for not all mean well to you both.
When you are through with all this then its left to you alone to decide either to go on or break the relationship.