Pregnancy test faint line

So I'm 13 weeks pregnant with my third child and I'm not showing at all and I just don't feel pregnant. So today I decided to just take another pregnancy test to see what it said and it was super faint, more so than the first time I took it over a month ago. I have a 10 month old and I am exclusively breastfeeding him so I really didn't think I was going to get pregnant since I had only had two very irregular cycles, but I thought I was pregnant and now I'm thinking that maybe I'm not or there's something wrong :( why would the test be so faint at 13 weeks?

I haven't been to the doctor yet because I have medi-cal and right before I realized I was pregnant my doctor that I had been going to for ten years sent me a letter saying they no longer accept my insurance, then we moved, so I need to find a new doc and make an appointment. But I thought I would see if you ladies had any insight as to why it's so faint.

Thanks.