well, I, myself, have recently experienced the "mature" pergnancy situation.

I am 40 (in March) and am now 32 weeks pergnant. I might add that I was NOT trying to get pregnant and was on contraception.

It was a nerve wracking time for me waiting to get the results of a positive when I FELT that I must be pregnant but was before the tests would conclusively prove it.
There are some quite accurate tests that show a correct 'positive' earlier than standard tests. I used them and they were correct, but I admit that I must have used 4 to 5 tests in paranoia over a 4-5 day period.
The only thing you can do is wait.
That and stop ALL medications that are harmful for the baby, eat well, start taking vitamins, minerals, iron and FOLIC ACID in case right now.
I had a miscarriage earlier this year (still not attempting to get pregnant but that is why I started contraception .. and got pregnant anyway

), and I think that it was due to the medications I was taking (as well as my nutritional status, but we won't go there.. I just had a Gastric Bypass).
So, do the RIGHT THINGS NOW... in case.
Sorry I can't help and be more supportive or specific.

When was the date of your last day of your last period?
(I am an RN, I might be able to help you calculate with more assurance).