Mama, I totally understand where you're coming from with the out of pocket cost, etc....here's the deal though:
Abx are really pretty much useless for sinus infections(thank goodness more people are paying attention to this lately and some good articles have actually come out about it)....and I would absolutely NEVER take abx for strep without confirmation that it was strep. The pregnant immune system can be really wacky and seriously, your sore throat could actually be an immune response, your body trying to fight off some virus...you could be really struggling to overcome something and taking the antibiotics could mess with your gut and hurt your ability to fight off this virus/illness, you know?
Abx are serious business for a pregnant lady who is dealing with an illness. The absolute worst time, in my mind, to take antibiotics, would be while pregnant, when there is an illness floating around the family. The abx are going to mess up your gut and make you MORE likely to stay sicker longer...and let's be honest, it sometimes feels like it's far away, but June is right around the corner.
If I found out I had strep, I would absolutely take them, because at that point the benefit outweighs the risks. If I had a sinus infection, abx wouldn't even cross my mind. If I didn't know WHAT I had going on with me for sure....there is nothing you could do to get me to take the abx.
You don't want to do something now which leads to you struggling to overcome low-level illness over the next few weeks....which, in turn, leads to you going into your birthing/PP time in a run down state. Believe me, after this whole thing with Norovirus, we are like SCRAMBLING to get better, because I am SO run down that it's like, scary crazy bad. If I don't get my iron levels up, my MW can't legally attend me at home. Yikes! I am totally in the grips of a run down state and I don't want to see you here. If I had to give birth tomorrow, I have no idea how I could do it. I'm so run down, I'm like a little weak kitten. Don't do something that puts you where I am right now...just run down and tired and "mildly ill" (for weeks and weeks).
In other words, mama, I totally get that it sucks....but it's worth the out of pocket expense to find out what is really wrong. I'm sorry. :( Can you look for some sort of crazy cheap, seedy type walk in clinic downtown? In your shoes, I would look for the closest citys walk in clinic for unisured or broke folks and be all pregnant and sympathetic and just be like "I can't afford to find out what is wrong, but I think it is strep and I just, I just...abaahabbhabaa(sobbing) I can't take it any moooooreee! Abahababahaabooobo(more sobbing)!!" - and let them take care of you. Worst case scenario, you find out what is or isn't wrong with you and can make a good choice based on that and the clinic will make a payment plan for what will most likely be a fee based on a sliding scale.
If it's strep, you've got to take care of it. If it's not strep, you really don't want to chance taking abx and hurting your bodies ability to get you well again for this spring.
Please keep us in the loop. I have been a sufferer, in the past, of multiple cases of bad strep and horrible sinus infections. I know what kind of pain you are talking about and I'm so so sorry.