Wrinklytum, reflux sounds quite possible, have you compared her behaviour with one of the checklists, e.g on \link{http://www.reflux.org/reflux/webdoc01.nsf/(vwWebPage)/AboutGERD.htm?OpenDocument\this page}? There are also many things you can do to reduce the severity of reflux, e.g. feeding the baby little and often, sitting them up for 1/2 hr after feeds, making sure they don't sit slumped in positions which can squash their stomach, avoiding clothes with tight waistbands, carrying them upright for long periods of time, elevating the head of their bed so they sleep at an angle (30 degrees is recommended, which is really very steep). If a doctor knows what they are doing, they may ask that you follow these 'lifestyle' changes before trying any medications.
However, if it's still bad, ime the doctors may not take any notice of you unless you really bother them about it. Okay, they will probably put you down as being an overanxious mum, but that's better than letting your child's condition get worse without doing anything about it. The weight gain thing is really a double edged sword, if your baby is not gaining weight the medics and health professionals do seem to pay more attention, but put them on low doses of the drugs (because the dose is calculated by weight), so they may not properly eliminate the reflux. But if your child is gaining weight they wonder what you're worried about, despite all the other symptoms.
Just so you know my background, my ds2 has severe reflux, and we had to go to the GPs about 5 or 6 times before they finally referred us to a paed at the local hospital. I was at my wits' end by this time. Luckily the paed knew a thing or two about reflux. I haven't always seen eye to eye with him but at this stage he immediately agreed with us that we were right and put ds2 on domperidone and ranitidine (which the GP wouldn't prescribe as they are not licenced for use on infants). They take up to 2 weeks to start working, and can be tricky to administer, but it really made a difference.
I hadn't clicked beforehand that the cough and runny nose were connected to reflux, but of course I've read about them since. Ds2 certainly seemed to always have them before he started the treatment, and when the doses got too low they came back (along with the whole writhing, screaming, vomiting thing).
I have loads of useful links, here are a few which you may or may not have already seen:
\link{http://www.infantrefluxdisease.com/about_infant_reflux.php\infantrefluxdisease.com} has a lot of useful info, including \link{http://www.infantrefluxdisease.com/seriously.php\how to get the doctor to take you seriously} and checklists of symptoms and complications so you can go to the doctor armed with notes in the kind of language they understand. I remember one of the things the dietitian really took notice of was that my ds would only take about 2 oz milk from a bottle at any time. I now know this isn't hugely unsurprising for a breastfed baby, but at least it made her sit up.
The \link{http://www.reflux.org/\PAGER} website is fairly comprehensive and they also have a facility where you can e-mail a volunteer for advice (someone who's been through having a child with reflux, so they know what you're going through). But the PAGER people seem to avoid talking about dosages of medications, I think because they want to work with the drugs companies rather than putting them off. On other sites you'll find far more honest discussion of actual dosages and treatments.
It can be pretty tough dealing with a refluxer so there are various forums out there, including one on \link{http://www.infantreflux.org/forum/default.asp\infantreflux.org}. Again, other people who have been through it or are going through it, tend to be the best ones to understand your position and offer help.
I hope your dd doesn't really have reflux, but if the information seems to fit your situation, at least you know there's help around.