Confused & worried - advise please

I have taken numerous pregnancy test all saying positive, pregnant only one came back at the start saying 'not pregnant' but since then maybe 10 tests saying pregnant. 
It took us 3.5 years to have our first baby via ICSI and he is 6 months old and we have conceived naturally without trying.
I'm just so so worried - I don't have any symptoms of being pregnant (last time I was really sick). The lines on the cheap ones are still showing faint and not getting darker - if I go by the clearblue test I'm just past 4 weeks where if I go by my lmp I'm 5 weeks.
I can't stop thinking of the worst what if I'm not pregnant maybe it's a cyst? Maybe I'm misscarrying? Never felt so worried and confused 😩 I have booked a private scan for Saturday but that's a whole 6 days and counting! If I'm only 5 weeks on Saturday as per clearblue test I will have to go back the following week for a scan.