(((hugs))) and well done for BFing for this long!
Could you post your LO's typical routine in terms of BFs, WU and nap times?
It may be that moving the top-up feed a little later might help (so just a v short A time after it before her nap), she probably isn't really hungry for it just an hour after a "main" feed, or perhaps she doesn't need a top-up so often. Or you could try splitting a BF so it is one side before nap, other side after nap.
It can be tricky at this age fitting in feeds and naps, when they seem to need both at the same time! It tends to get a little easier once solids are started I find though (which I guess you will be starting soon), as they can then go a bit longer between BF/milk feeds and you can just do them on WU from naps, first thing in the morning, and at BT.
Is she BFing at night?
Have you had a look at the sample routines? there might be some ideas for you there:chronological EASY samples, 4-6 months