it's usual to start having some symptoms as you hit 40 but it's not unheard of in your mid to late thirties. trouble is most ladies aren't really aware of perimenopause and it's only in retrospect that they realise they were having symptoms, dreadful pms being a very common sympton to start with. it doesn't necessarily follow that you'll be the same as your mum either, it definitely didn't for my sister and i.
a blood test probably wouldn't show anything up yet, hormonal fluctuations being what they are but defo have a chat with your doctor (or a different one in the practice?), they may have invented some wonder cure - ha, we wish!! :)