These past couple weeks I've been more aware about OPSEC and would like some input from you guys. Current set up is running Tor Browser Bundle straight from Windows 7 on one of two home broadband connections. I don't use TAILS. I buy bitcoins by cash deposit via localbitcoins. I don't tumble them. I've only made four small purchases in the last two months but soon need to make two more, again small quantities. I thought I was doing enough for just buying small amounts but I'm starting to feel uneasy about my set up now. Am I just being paranoid or I am considered low-hanging fruit?
You're fine. Low quantity envelope-sized purchases and you have nothing to be paranoid about.