I've Been On The Pill For Several Years Now And

I've been on the pill for several years now and was in a long-term relationship that ended in October (subsequently, also the last time I was sexually active). I stayed on the pill after the break-up and had normal withdrawal bleeding for four months (November, December, January, and February). However, in March, the withdrawal bleeding was extremely light, and I've gained (without explanation) over ten pounds as well as developed a squishy bump. I last had intercourse 22 weeks ago. Could I be pregnant, despite the normal/moderate-to-heavy withdrawal bleeds for four months?