chlorphenamine (antihistamine) for insomnia in pregnancy?

[MultiMagpie]

I’ve gone through two years of IVF and now finally pregnant with my miracle baby. I’m currently 19 weeks pregnant. Nearly my whole adult life I’ve had insomnia and obviously when I became pregnant I could no longer take my usual tablets. I saw on the NHS website that chlorphenamine is safe to take and is a drowsy antihistamine and I’ve been taking it on and off since the first trimester, not having said anything to a midwife or GP because I just assumed it was a weak drug. Went the other day to a different pharmacy who asked if I was pregnant and they put the fear of god into me that they can’t give it to me, a GP should prescribe it etc and then I fell down a Google wormhole where half say it’s fine and half don’t, so I’ve been terrified to take it ever since but I’m not either getting two hours a night or none at all, so miserable.

Has anyone taken chlorphenamine or other antihistamines in pregnancy? Is it fine to take? I’ve tried magnesium spray and cherry juice but to be honest, my insomnia is so bad homeopathic things just don’t work.