Test or wait it out?

I have been breastfeeding my son, who will be one on 12/20. My son still breastfeeds on demand, and eats solids as well. My son had a string of colds in September and October. When he was not feeling well, he was nursing a lot less due to congestion. I ended up getting my 1st period on 10/6, and got another 1 on 11/6. I have not had a period since then. My son did go back to a normal nursing schedule by middle of October. I have been feeling cramps, and back ache like i am going to start, and have felt them for about 2 weeks now. I have been kinda tired, and the need for water has increased. What keeps me thinking im either just irregular and not pregnant is there have been no changed with my breasts or milk supply. I admit my milk when i pumped at my pt job looked a bit more on the bluer side, i still made my normal amount. My breasts don’t look any different, not sore, and my son is nursing fine. Would you ladies buy a test or wait it out? Is it possible to be pregnant while breastfeeding and have no breast/ supply changes yet? I have 3 children, but this is the first one where i breastfed for more than a few months. Thank you ahead of time for any input or advice!