OK, a few things here. Often your body takes a couple months to fully get back in the groove of being not pregnant, but sometimes it's rather quick. Breastfeeding usually keeps your body from ovulating for the first 6 months (when the baby is relying on your body for 100% of her food). But if you start with supplementing baby food before that, that goes out the window.

If you think you may be pregnant, you can do a couple things. 1) HPT - if it turns out negative, test again in a couple weeks if you still think you may be pregnant as you may not have enough hormones to show positive. 2) go to your doctor and have them do a blood test to confirm. If you are not pregnant, they can also see if anything is being screwy or if it's normal for your body to be doing what it's doing. It's likely normal, but always good to check it out too if you have any questions.

GL, and congrats on your darling!