TTC problems

Hey girls, I’ve been trying to conceive since the last week of August. I haven’t had a period since before July 2017 when I was pregnant with my first, and I was on the depo shot birth control 6 weeks after I gave birth so I haven’t had a period in 2 years. I stopped taking birth control at the end of August. I don’t know when I should be taking pregnancy tests!! I had a very very small period (mostly spotting) a few weeks ago. We have been actively TTC but I feel like I’m wasting so much money on pregnancy tests whenever I feel the slightest bit of symptoms. Has anyone else been in this position? I drink alcohol pretty much every day so I’m worried I’m going to harm my pregnancy but at the same time I don’t know if I’m pregnant or not!! What should I do??