Are they wanting to put you on Prometrium? Are you typically regular? It is commonly used during fertility issues. Prometrium will help build up the lining of the uterus (and also in the tubes if the endometrium has grown in there, thus possibly blocking the tubes). After ten days, you usually stop taking the Prometrium (withdrawal) and a period starts shortly thereafter. You will have a 'defined' period where they can do a day 3 blood draw, perform glucose tolerance tests and other blood levels like FSH. Prometrium is COMMONLY used in fertility workup.
If you don't mind me asking, since you're in Chicago which fertility doctor are you seeing? I've seen two - one was horrible and the other was absolutely outstanding. Is this your first time with a fertility specialist? You may want to try and keep an open mind as far as what they want you to do because this is their line of expertise. You want a baby - they can help. It might be your hormones that are preventing you from conceiving/carrying a child and perhaps they need adjusting to make pregnancy a possibility? Also, pills have changed dramatically in the last 18 years. The doses are lower than ever and likely different from what you experienced.
Ask lots of questions. Make sure you're working with an RE who will explain everything to you - and if they want to jump straight to IVF at least have them tell you why they ruled out other less complicated attempts. Unless you're paying out of pocket for this, I'd be very surprised if your insurance would even allow you to jump straight to IVF without trying more conventional, conservative routes. I know my insurance required typically two failures at each 'fertility level' before I got bumped up to the next level.
Finally, if you are really set on continuing doing things the natural way two great resources are Toni Weschler's Taking Charge of Your Fertility book and the www.fertilityfriend.com website. Both are full of helpful information regarding conceiving.
Best wishes to you!