A girls number isn't too important, any girl that has been to uni is likely to be into double figures by the end of it.
Guys have a affinity with smashing as much as they can whilst at uni but then don't like it when girls have a high number, who do you think you are smashing? If you want low numbers then stop smashing anything that moves collectively or date 16 year olds.
The oddest thing here is that she went off to be with someone else for a bit and came crawling back, how do you not feel like you are second best?
However, if you enjoy chilling with her and the rest of it then just keep doing it, just like all early relationships proceed at arms length, if it develops into more then great, if not then at least you tried!