Ok for 16 weeks & BF the 4.30am feed is very normal... so it is the fact you can't resettle her back to sleep that is the issue, is it that you can't settle without feeding, or that she only settles with a feed... if it is that she only settles with a feed... well that is because that is what she NEEDS at this age.
For her age I think her day awake time is a bit long, so I think overtiredness is the issue
for a 3.5-4mo, you would expect 1.5 -2 hours awake time (2 hours is pushing it for many babies) so you would actually be looking at 3 x 2 hour naps in the day & about 10.5 - 11 hours sleep overnight.... but you would also expect 2 (& possibly 3 night feeds... including the df to be part of that time)
It is actually quiet normal for them to be hungry at 4.30 & not so much at 7am, so try to unlatch her at 4.3o, when her sucking stops being strong... I found that it wasn't until my ds started on solids at 6months (I don't suggest strating them eary to solve this problem, as it can sometimes lead to life long digestive problems starting solids too early) that the what slowly moved from a 4 to 5, then 6am feed dissapeared.
hang in there she is only young & if EASY is going well, it will improve, it just takes time & being tired is VERY normal... you will find as your lo gets older (7-8months) night wakings for developmental reasons often occur, so I think it is best to learn as a mother an earlier bedtime & naps while the baby does are NORMAL, not a luxury
HTH