Strong symptoms? Possible twins?

I took letrozole this month to get pregnant which has a possibility of multiples, my symptoms have been strong and getting stronger daily. Currently 4w 4d and I pee constantly, nausea is awful along with heart burn. Wicked tender breasts and I’m always tired. Also had my first positive at 20 days into my cycle 3 days after I felt the implantation. I keep thinking I’m having twins my boy friend just laughs but I swear I’ve never had symptoms this strong so early with either of my past pregnancies (I had a previous miscarriage and an ectopic)