I'd highly recomend you don't try keeping your LO up longer. Thats a pretty good night sleep for 13 weeks. If you try to keep her up you'll just end up with an overtired and over stimulated baby, and then all hell could brake loose.
My LO also goes to bed at 7pm, she has been since 10 weeks, she started with the same basic routine as your LO. She'll now sleep right through till 7-8 am with an 11pm dreamfeed. She's now 4 months old (on X-Mas) it takes time before they sleep right through, just be patient and keep up what your doing. They'll sleep through for you before you know it

Your doing a great job.