Hi I am just looking for a bit of advice. I am a 23 year old woman who has been dealing with a lot of concerning symptoms.

I am normally perfectly healthy except for hypothyroidism which has been managed for the past three years with no issue. But for the past 10-ish months I have been increasingly unwell and I'm worried the doctors are unwilling to listen to my concerns either because I'm young or because I have been very upfront with my concerns of cancer due to a very strong family history. 
 

Quick breakdown, I have family history with breast cancer (BrCA1 gene likely present), ovarian cancer, lung cancer, pancreatic cancer and lymphoma (either Hodgkin or non-hodgkins, not entirely sure). This is also all multiple occurnaces of each cancer except lymphoma across the past 4 generations. How fun, right? 
 

Now for my symptoms; for the past 10 months I have started to become increasingly unwell. It started with several bouts of illness back-to-back, colds, chest infection, ear infection etc. I have been catching almost any illness or infection I come in contact with where normally I'm great at fighting off illness. Then I started getting real bad knee pain, then back pain. Worse at night, aching and very tender and it wakes me up during the night. Then fatigue, which started manageable but had become impossible to deal with. I've had to take time off work because I genuinely get exhausted and out of breath just walking up the stairs and I am napping daily, which I have never done before because naps normally leave me feeling groggy and worse off. I can't even do grocery shopping because just walking around the shop makes me tired and lightheaded. My appetite has disappeared and most recently I have developed a like pinprick type rash which is itchy but has been there for about two weeks (went to my GP for it and they confirmed not meningitis and they said to just keep an eye on it and contact them again if it spreads which it hasnt). 
 

I feel like with how I've been feeling I have reason to be worried. But the doctors have been fobbing me off. I have seen five different doctors in my GP. They have issues me seven blood tests over the 10 months to check my thyroid and liver function which all came back fine. One of the doctors told me "this is just how young women feel sometimes" like what? This is not normal, right? 
 

I don't know what to do because there is really only one GP in my area and I dont drive to try to see another one even if they would take me on but I don't know what else to do. 
 

Are my concerns valid? How should I proceed in trying to get a doctor to take me seriously?